Combined high power rf/microwave amplifier with multiple power amplifier units and automatic failure protection

ABSTRACT

A high power RF or microwave amplifier may amplify an RF or microwave input signal. The high power RF or microwave amplifier may include an input signal divider (DIV) that has an input port that receives the RF or microwave input signal and that divides this input signal into multiple sub-input signals; multiple power amplifier units (PAUs), each having an input port that receives an RF or microwave signal, an output port that delivers an amplified version of the received RF or microwave signal, and an interface port; an interface control unit (ICU) that communicates with each PAU through its interface port; and an output signal switching combiner unit (SCU) that coherently sums the outputs of the on-line PAUs and delivers this to an output port. The ICU may set one or more of the PAUs to amplify one of the multiple sub-input signals (hereinafter referred to as on-line PAU in on-line mode); monitor each on-line PAU to verify that it is operating within one or more pre-determined PAU specifications; and upon detecting that one of the on-line PAUs is no longer operating within the one or more pre-determined PAU specifications (malfunctioning PAU), set the malfunctioning PAU not to amplify one of the multiple sub-input signals and not to be available to be switched to the on-line mode by the ICU (hereinafter referred to as off-line PAU in off-line mode).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims priority to U.S. provisionalpatent application 62/065,390, entitled “HIGH POWER DENSITY RF/MICROWAVESOLID STATE POWER AMPLIFIER ARCHITECTURE,” filed Oct. 17, 2014, attorneydocket number 094249-0011, and U.S. provisional patent application62/096,811, entitled “ULTRA HIGH POWER SOLID STATE (M+N) REDUNDANT CHPAARCHITECTURE,” filed Dec. 24, 2014, attorney docket number 094249-0012.The entire content of both of these applications is incorporated hereinby reference.

BACKGROUND

1. Technical Field

This disclosure relates to high power, solid state amplifiers for radiofrequency and microwave signals, including pulse and CW radar signals.

2. Description of Related Art

RF and microwave power amplifiers may need to operate under pulsedconditions, such as in civilian and military radar systems. They mayneed to provide a high peak power to gain surveillance/transmit distancecapacity.

Klystron and TWT systems may deliver very high transmit power(megawatts), while occupying relatively small physical volumes. However,these radar systems may provide a mean time between failures (MTBF) ofonly hundreds of hours. This can be problematic in mission-criticalapplications, such as in radar on a military ship or in an airportcontrol tower.

Solid state power devices are now capable of delivering 1 kW peak powerper device or more. Efforts have been made to achieve solid state highpower (>>10 kW) amplifiers (SSHPAs) by combining multiple solid statepower devices utilizing multiple stage, conventional passive combiningschemes, such as balun, Wilkinson, hybrid, and radial combiners.However, the power level and power density of SSHPAs may not be as greatas the rival Klystron.

Reliability can also be a problem. The MTBF of a power amplifier unit(PAU) that includes one or more power devices may be the replica of thefailure rate λ_(PAU) (per 10⁶ hours) where the power device failure rateλ_(p) dominates the total λ_(PAU). According to MIL-HBK-217:

λ_(p)=λ_(b)π_(T)π_(A)π_(M)π_(Q)π_(E)  (1)

where π_(T), π_(A), π_(M), π_(Q), and π_(E) are as specified below.

The temperature factor may depend on the junction temperature T_(J) of apower device (π_(T)=0.1 with T_(J)=100° C.) as follows:

π_(T)=0.1e ^({−2903(1/(TJ+273)−1/373)})  (2)

Application factor may be irrelevant to the specific power device(π_(A)=0.64 with 4% duty cycle as an example):

π_(A)=0.06(Duty Cycle %)+0.4  (3)

Matching factor: π_(M)=1.0 for the Input and Output match deviceQuality factor: π_(Q)=5.0 for Lower PartEnvironmental factor: π_(E)=4.0 for naval sheltered NS as an example

For a power device used in a naval-sheltered environment, assuming 100°C. peak junction temperature with ˜4% duty cycle pulse operation:

λ_(p)=1.28λ_(b)  (4)

where the λ_(b) base failure rate may be determined by operatingfrequency F in GHz and peak power P in watts:

λ_(b)=0.032e ^({0.354(F)+0.00558(P)})  (5)

Assuming an operating frequency F=1.0 GHz, the following Table 1presents estimated MTBF of SSHPA utilizing conventional combiningarchitecture with various power levels per device.

Assuming an operating frequency F=1.0 GHz, the following Table 1presents estimated MTBF of SSHPA utilizing conventional combiningarchitecture with various power levels per device.

TABLE 1 Estimated MTBF of Conventionally Combining SSHPA Power DeviceConventionally Combined to form HPA Estimated MTBF (Hr) for HPA* PeakPower λp (per MTBF including power devices and passive components (W)106 Hr) (Hr) 5 kW 10 kW 20 kW 40 kW 500 0.74 1,350 kHr 75 kHr 37.5 kHr18.75 kHr 9.375 kHr 1000 12.08 82.7 kHr 9.2 kHr 4.6 kHr 2.3 kHr 1.15 kHr2000 3203.44 310 Hr 69 Hr 35 Hr 17.5 Hr 8.75 Hr *The estimation is basedon 1.5 times total power device failure rate, as the overall failurerate of SSHPA. The actual MTBF of SSHPA may vary depending upon specificapplications, environments, etc.

Thus, further increasing device unit power may not reliably achieve aneeded high power. With moderate unit power, the reliability of powerunder 10 kW may be feasible based on conventional combiningarchitecture. However, it may not be sufficiently reliable for powerlevels greater than 100 kW. The use of lower power devices in HPA mayalso create mechanical complications and may not have a needed powerdensity.

This analysis may apply for ultra-long pulse, ultra-high duty cycle, andCW operation power amplifiers with lower output power, becausesignificant junction temperature increases may dramatically decrease thereliability of HPA according to equations 2 and 3.

In general, RF and microwave SSHPAs utilizing conventional combiningarchitecture summing up multiple solid state power devices can faceultra-high power and ultra-high power density challenges in comparisonto rival technologies due to limitations in power device availabilityand/or reliability.

Therefore, the need continues for an RF or microwave amplifier that canhandle ultra-high power in excess of 10 kW with high power densityand/or ultra-reliability for various signaling applications, includingpulsed and continuous wave (CW) operations.

SUMMARY

A high power RF or microwave amplifier may amplify an RF or microwaveinput signal. The high power RF or microwave amplifier may include aninput signal divider (DIV) that has an input port that receives the RFor microwave input signal and that divides this input signal intomultiple sub-input signals; multiple power amplifier units (PAUs), eachhaving an input port that receives an RF or microwave signal, an outputport that delivers an amplified version of the received RF or microwavesignal, and an interface port; an interface control unit (ICU) thatcommunicates with each PAU through its interface port; and an outputsignal switching combiner unit (SCU) that coherently sums the outputs ofthe on-line PAUs and delivers this to an output port. The ICU may setone or more of the PAUs to amplify one of the multiple sub-input signals(hereinafter referred to as on-line PAU in on-line mode); monitor eachon-line PAU to verify that it is operating within one or morepre-determined PAU specifications; and upon detecting that one of theon-line PAUs is no longer operating within the one or morepre-determined PAU specifications (malfunctioning PAU), set themalfunctioning PAU not to amplify one of the multiple sub-input signalsand not to be available to be switched to the on-line mode by the ICU(hereinafter referred to as off-line PAU in off-line mode).

The ICU may set one or more of the PAUs not to amplify one of themultiple sub-input signals and to be available to be switched to theon-line mode (hereinafter referred to as standby PAU in standby mode).Upon detecting a malfunctioning on-line PAU, the ICU may change one ofthe standby PAUs to the on-line mode, thereby causing suchpreviously-standby PAU to amplify one of the multiple input signals andto thereby replace the malfunctioning on-line PAU.

The ICU may monitor each standby PAU to verify that it is operatingwithin the one or more pre-determined PAU specifications. Upon detectingthat one of the standby PAUs is no longer operating within the one ormore pre-determined PAU specifications (malfunctioning standby PAU), theICU may change the malfunctioning standby PAU to the off-line mode,thereby preventing the PAU from being one of the standby PAUs that ischanged to the on-line mode in response to detection of a malfunctioningPAU.

The input signal may include a series of pulses. The ICU may begin andcomplete both of the following between two sequential pulses in theseries of pulses: changing a malfunctioning PAU to the off-line mode;and changing one of the standby PAUs to the on-line mode.

The pulses may have a duration of no less than 1 μs and a period betweenpulses may be no less than 20 μs.

The ICU and the SCU may isolate the standby and off-line PAUs from theoutput of the SCU and the outputs of the on-line PAUs.

The high power amplifier may automatically shut down after the ICUdetects more than a pre-determined number of malfunctioning on-linePAUs.

The output port of the SCU may present and maintain a substantiallyconstant impedance, notwithstanding changes in the number of on-linePAUs, so long as the changes do not reduce the number of on-line PAUsbelow a threshold.

The SCU may continue to coherently sum the outputs of the on-line PAUsand to deliver this to the output port, even when there is no PAU in thestandby mode to replace a malfunctioning on-line PAU.

The a malfunctioning PAU may be able to be safely removed from the highpower amplifier and replaced with a replacement PAU during operation ofthe high power amplifier, without interfering with or degrading theperformance of the high power amplifier during or after the removal andreplacement.

The high power amplifier may include one or more blind mate connectorsthat detachably connect each PAU to the high power amplifier throughmultiple electrical connections.

An on-line PAU may be able to be deliberately or accidentally removedfrom the high power amplifier during operation of the high poweramplifier, without interfering with or degrading the performance of thehigh power amplifier during or after the removal.

The high power amplifier may include a sense switch that senses theremoval of each PAU from the high power amplifier. The ICU may quicklyplace any such removed PAU that is in the on-line mode into the off-linemode before any of its multiple electrical connections are broken by thecontinued removal of the PAU.

The high power amplifier may include multiple power supply units (PSUs).

Each PSU may power a different one of the PAUs.

The ICU may monitor each PSU to verify that it is operating within oneor more pre-determined PSU specifications. Upon detecting that one ofthe PSUs is no longer operating within the one or more pre-determinedPSU specifications (malfunctioning PSU), the ICU may:

if the malfunctioning PSU is powering an on-line PAU: changes theon-line PAU that is powered by the malfunctioning PSU to the off-linemode, thereby causing this on-line PAU not to amplify one of themultiple sub-input signals, not to be available to be switched back tothe on-line mode by the ICU, and not to consume power from its PSU; andchanges one of the standby PAUs to the on-line mode, thereby causingsuch previously-standby PAU to amplify one of the multiple input signalsand to consume power from its corresponding PSU, thereby replacing themalfunctioning PSU; and

if the malfunctioning PSU is powering a standby PAU, changes the standbyPAU that is being powered by the malfunctioning PSU to the off-linemode.

The high power amplifier may automatically shut down when the ICUdetects more than a pre-determined number of malfunctioning PSUs.

All of the PAUs and outputs from all of the PSUs may be connected to acommon power supply bus.

The high power amplifier may include a diode connected in series betweeneach PSU and the common power supply bus that prevents a malfunctioningPSU from loading the common power supply bus.

The ICU may: monitor each PSU to verify that it is operating within oneor more pre-determined PSU specifications; and upon detecting that oneof the PSUs is no longer operating within the one or more pre-determinedPSU specifications (malfunctioning PSU), deactivate the malfunctioningPSU.

Any of the PSUs may be able to be safely removed from the high poweramplifier and replaced with a replacement PSU during operation of thehigh power amplifier, without interfering with or degrading theperformance of the high power amplifier during the removal andreplacement.

The high power amplifier may include one or more blind mate connectorsthat detachably connect each PSU to the high power amplifier throughmultiple electrical connections. A sense switch may sense the removal ofeach PSU before any of the multiple electrical connections are broken.

The DIV and SCU may be in a single common compartment.

The DIV and SCU may be detachably connected to the high power amplifierthrough one or more blind mate connectors.

The PAUs and PSUs may be water cooled.

All of the components within the PAUs may be solid state.

The high power amplifier may produce a peak power output of at least 40kW at a frequency of at least 800 MHz with at least a 20% bandwidth.

The high power amplifier may have a peak power density of at least 10W/in3.

The high power amplifier may have a mean time between critical failures(MTBCF) of at least 80,000 hours in naval shelter environments with atleast 3.87% pulse duty factor.

The ICU may remove the input signal to DIV before setting themalfunctioning on-line PAU to the off-line mode and a standby PAU to theon-line mode.

The ICU may set a malfunctioning on-line PAU to the off-line mode andchange one of the standby PAUs to the on-line mode to replace it withinno more than 20 μs (microseconds).

These, as well as other components, steps, features, objects, benefits,and advantages, will now become clear from a review of the followingdetailed description of illustrative embodiments, the accompanyingdrawings, and the claims.

BRIEF DESCRIPTION OF DRAWINGS

The drawings are of illustrative embodiments. They do not illustrate allembodiments. Other embodiments may be used in addition or instead.Details that may be apparent or unnecessary may be omitted to save spaceor for more effective illustration. Some embodiments may be practicedwith additional components or steps and/or without all of the componentsor steps that are illustrated. When the same numeral appears indifferent drawings, it refers to the same or like components or steps.

FIG. 1 is a simplified block diagram of an example of a redundant,combined high power amplifier (CHPA) architecture.

FIG. 2 is a simplified block diagram of an example of a 40 kW (9m+1 n)combined high power amplifier (CHPA) with an interface control unit andother control components.

FIG. 3 illustrates the mechanical layout of an example interface betweena PAU and a combined input power divider/switching combiner unit.

FIG. 4 illustrates an example of a prior art high power combinedamplifier that uses a conventional radial combiner with “n” inputs.

FIG. 5 illustrates an example of a switching combiner unit (SCU) circuitthat can automatically and safely disconnect an input port in responseto a shutdown command.

FIG. 6A illustrates an exploded view of an example of a switchingcombiner unit; FIG. 6B illustrates an enlarged view of a port section ofthe switching combiner unit; and FIG. 6C illustrates the switchingcombiner unit fully assembled.

FIG. 7 is a schematic of an example of an N-way input power divider thatmay provide high port-to-port isolation.

FIG. 8A is an exploded view of an example of a 10-way input powerdivider;

FIG. 8B illustrates an enlarged view of a portion of a PCB within thedivider; FIG. 8C illustrates a rear view of certain components of thedivider; and FIG. 8D illustrates the divider fully assembled.

FIG. 9 is a block diagram of an example of a 5 kW compact pulse radarpower amplifier with monitor, control, and protection features operatingin low L-Band.

FIG. 10 illustrates an example of a T-plate structure that may be usedto compactly contain and cool the components in the compact pulse radarpower amplifier shown in FIG. 2.

FIG. 11 illustrates an example of high thermally-conductive materialthat may be embedded in the thermal path of a T-plate structure toimprove thermal conductivity.

FIG. 12 illustrates an example of a thermal model for the T-platestructure illustrated in FIGS. 10 and 11.

FIG. 13 illustrates an example of a layout that may be used for eachbasic amplifier module (BAM) that may provide an output of at least 1.25kW.

FIG. 14 illustrates an example of a compact high power combiner modulewith RF interfaces perpendicular to the layout plane and may alsoprovide forward/reflected power coupling functions.

FIG. 15 illustrates an example of a compact driver/divider with RFinterfaces perpendicular to a layout plane, and includes DCdistribution, controls, driver amplification, and divider circuitry.

FIGS. 16A and 16B are an example of different views of direct interfacesbetween a driver/divider module and BAMs, as well as direct interfacesbetween an output module and BAMs. The BAMs may amplify their respectiveinputs and each delivers 1.25 kW.

FIG. 17 is an exploded view of an example of a 5 kW compact high poweramplifier that uses a T-plate structure in a compact design.

FIG. 18 illustrates an example of a solid state amplifier, a coolingplate, and a single bolt that may be used to easily attach and detachthem from one another.

FIG. 19 illustrates an example of a fully assembled 5 kW compact highpower amplifier utilizing a T-plate structure.

FIG. 20 illustrates an example of a water cooling system for an example(9+1)CHPA, showing liquid cooling distribution from an inlet to tenparallel cooling plates for ten PAUs.

FIG. 21A illustrates an example of a water cooling system for a(9+1)CHPA, that includes manifolds and cooling plates. FIG. 21Billustrates an example of the cooling plate CP01 illustrated in FIG. 21Aand shows how PAUs may electrically interface with a DIV/COM assembly,power supply bank (PSB), and interface control unit (ICU).

FIGS. 22A and 22B illustrate different views of an example of a compact,modular 40 kW (9+1)CHPA with electrical and thermal interfaces.

FIG. 23 illustrates a cut away and partially exploded view of the CHPAillustrated in FIGS. 21A and 21B and illustrates the integration ofmultiple assemblies, like PAUs, a cooling assembly, a DIV/SCU assembly,and an ICU assembly.

FIG. 24 illustrates a redundant (m+n) power supply bank ((m+n)PSB),along with an (m+n)CHPA.

FIG. 25 illustrates an alternate redundancy design for a power supplybank (PSB) that has (i+j) PSUs that form paralleling (i+j) redundancy

FIGS. 26A and 26B illustrate two views of a (2+1)PSB configuration withthe same height and depth dimensions as in a (9+1)CHPA, so that a pairof (9+1)CHPA/(2+1)PSB can be readily integrated as one entity.

FIGS. 27A-27C illustrate various components in an example of a (9+1)CHPAand (2+1)PSB set up for an SPS-49 platform.

FIG. 28 illustrates an example of a more than 280 kW SSTx that combineseight modular redundant (9+1)CHPAs utilizing hybrid combiners to replacea legacy Klystron transmitter for an SPS-49.

FIGS. 29A-29E illustrate examples of various components that may be partof an ultra-high power SSTx. FIG. 29A illustrates a CHPA module; FIG.29B illustrates a PSB module; FIG. 29C illustrates an IDD module withPSUs; FIG. 29D illustrates an ICU module located in an IDDM; and FIG.29E illustrates a 4-way OCM with an output coupler.

FIG. 30 illustrates an example of a legacy SPS-49 transmitter.

FIG. 31 illustrates an example of a solid state upgrade following theteaching herein that uses only two existing bays, leaving the middle bayfor maintenance access.

FIG. 32 illustrates an alternative forward fit upgrade proposal for theSPS-49 radar transmitter using two 901D racks.

FIG. 33 illustrates an example of a 10-way input power divider andswitching combiner unit (DIV/SCU) combined into a single unit.

FIG. 34A illustrates an example of an input/output constellationarrangement of connectors in a (7+1)DSCU design that may connect tomultiple PAUs. FIG. 34B illustrates an example of a back side of a PAUconfigured to slidably engage connectors on the DSCU illustrated in FIG.34A.

FIG. 35A illustrates another example of an input/output constellationarrangement of connectors in a (7+1)DSCU design that may connect tomultiple PAUs with uniform angle separation between adjacent branches.FIG. 35B illustrates an example of a PAU configured to slidably engageconnectors on the DSCU illustrated in FIG. 35A.

FIG. 36A illustrates another example of an input/output constellationarrangement of connectors in a (7+1)DSCU design that may connect tomultiple PAUs with uniform angle separation between adjacent branches.FIG. 36B illustrates an example of a PAU configured to slidably engageconnectors on the DSCU illustrated in FIG. 36A. FIG. 36C illustrates anexample of optimal layouts for the SCU portion of the DSCU illustratedin FIG. 36A utilizing the same assemblies for all branches.

FIGS. 37A and 37B illustrate different views of an example of interfaceconnections between a switching assembly and a transmission lineassembly, and then to an interface of a PAU in an example of (7+1)DSCU.

FIGS. 38A and 38B illustrate different views of an example of interfaceconnections between a divider assembly and a switch assembly, and thento an interface of a PAU input in an example of (7+1)DSCU.

FIGS. 39A and 39B illustrate an example of a consolidated (7+1)DSCUwhich may have a significant proportional profile reduction incomparison to the (9+1)DIV/SCU shown in FIG. 33 and which may beassembled with matched cables.

FIGS. 40A and 40B illustrate different views of an example of a 30 kW(7+1)CHPA utilizing a (7+1)DSCU for ultra-high power RF with a highpower density.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Illustrative embodiments are now described. Other embodiments may beused in addition or instead. Details that may be apparent or unnecessarymay be omitted to save space or for a more effective presentation. Someembodiments may be practiced with additional components or steps and/orwithout all of the components or steps that are described.

The following abbreviations are used in this disclosure:

Ao Operation availability

BAM Basic amplifier module

OAF Canadian Air Force

COM Combiner

CHPA Combined high power amplifier

DAU Driver amplifier unit

DIV Divider

DSCU Divider switching combiner unit

HPA High power amplifier

ICU Interface control unit

ICM Interface control module

IDD Input driver divider

IDDM Input Driver and Divider Module

LRU Line replaceable units

m Normally online LRUs

n Normally standby LRUs

MTBCF Mean time between critical failures

MTBF Mean time between failures

OCM Output combining module

PAE Power added efficiency

PAU Power amplifier unit

PSB Power supply bank

PSU Power supply unit

SCU Switching combiner unit

SS Solid state

SSHPA Solid state high power amplifier

SSTX Solid state transmitter

Architectures for various ultra-high power RF and/or microwavesolid-state (SS) combined high power amplifiers (CHPAs) will now bedisclosed.

Built-in redundancy may be provided. The CHPA may be configured usingmultiple, identical solid state (SS) power amplifier units (PAUs), whichmay be line replaceable units (LRUs). The CHPA may have “m” online PAUsand “n” standby PAUs. The “m” online PAUs may be coherently combined todeliver an ultra-high power output. Each of the “n” standby PAUs in astandby mode is available to be automatically switched online to replacea failure in one of the “m” online PAUs.

A divider (DIV) may divide an input signal into multiple input signals,one for each PAU. A switching combiner unit (SCU) may combine theoutputs from all of the online PAUs.

The CHPA may automatically detect a failure in any of the “m” onlinePAUs. The CHPA may also automatically replace an online PAU that hasbeen detected to have failed with a standby PAU (failover), ifavailable. Then, the failed previously online PAU is placed in anoffline mode.

The CHPA may effectively remove the failed LRU from the critical pathand thus provide continuous CHPA operation. The redundant architecturewith automatic failure detection and replacement may enable an SS CHPAto deliver ultra-high power with outstanding operational availabilityand system reliability.

The CHPA architecture may also provide graceful degraded operation ifmore than “n” LRUs fail. In such a case, the SCU's impedance mayautomatically optimize to ensure optimized (high) combining efficiency.

A failed offline LRU may be removed for repair without interruptingoperation. One or more of the online LRUs may also be safely removed,again without operational interruption.

True, hot swappable functionality may thus be provided by a combinationof these features.

Multiple CHPAs can be combined into a single ultra-high power amplifierto meet higher system power levels and greater reliability requirements.The various features discussed herein may enable an ultra-high power SSCHPA to be constructed that meets or exceeds mission criticalapplication requirements, such as with coherent radar transmittersystems.

FIG. 1 is a simplified block diagram of an example of a redundant,combined high power amplifier (CHPA) architecture. As illustrated inFIG. 1, the CHPA may include “m” online high power amplifiers, such asPAUs 101 and 103; “n” standby high power amplifiers, such as PAUs 105and 107, an input power divider (DIV) 109, and a switching combiner unit(SCU) 111.

Each high power amplifier, such as PAUs 101, 103, 105, and 107, may be ahigh power solid state amplifier capable of producing a high poweroutput, such as in the range of 2 to 5 kW or 1 to 10 kW. Each high poweramplifier may be configured to amplify input signals in the RF ormicrowave frequency range. The signals may be pulsed, continuous, or ofany other type.

The input power divider (DIV) 109 may be a divider circuit that dividesa signal at its input 113 into several outputs, one for each PAU. Theoutputs may each have the same amplitude and phase characteristics. Eachsignal for an online PAU may be delivered to the online PAU to beamplified. Each signal for a standby or an offline PAU may be terminatedin the input of the PAU not to be amplified.

The switching combiner unit 111 may coherently sum up the outputs fromeach online PAU into a single output at an output 115. The switchingcombiner unit 111 may also isolate the output port of standby andoffline PAUs from the outputs of SCU and online PAUs.

The system may include an interface control unit (not shown in FIG. 1,but shown in FIG. 2 as ICU 250) that communicates with controllersbuilt-in the PAUs and that detects when one of the online PAUs fails.The interface control unit may automatically deactivate a PAU that hasbeen detected to have failed with a standby PAU, switching the failedPAU to offline and one of the standby PAUs to online. The interfacecontrol unit may similarly command the switching combiner unit 111 tostart combining the output from the activated PAU and to isolate thecombined output from the failed PAU.

The number “n” of standby units may be based on a target MTBF of thePAUs and take into consideration other factors, such as otherreliability requirements, size limitations, and/or cost limitations.

The architecture may not allow a PAU failure to interrupt operation ofCHPA. Only the input power divider 109 and the switching combiner unit111 may be in the radio/microwave signal critical path.

The mean time between critical failure (MTBCF) and operationavailability (A_(O)) of the described CHPA may be expressed as:

$\begin{matrix}{{MTBCF}_{CHPA} = \frac{{MTBF}_{DIV}{MTBF}_{SCU}}{{MTBF}_{DIV} + {MTBF}_{SCU}}} & (6) \\{A_{OCHPA} = {\left\{ \frac{{MTBF}_{DIV} - {MTR}_{DIV}}{{MTBF}_{DIV}} \right\} \left\{ \frac{{MTBF}_{SCU} - {MTR}_{SCU}}{{MTBF}_{SCU}} \right\}}} & (7)\end{matrix}$

where MTR stands for mean time to replace.

A 40 kW ultra-high power HPA may utilize a (9m+1 n) redundancy schemefor shipboard applications. The practical MTBFs for the PAUs, DIV, andSCU may be greater than 50 kHrs, 500 kHrs, and 150 kHrs, respectively.

The design goal of the MTR for the DIV and the SCU may be 2 hours.Accordingly, the DIV and SCU designs may ensure in this example a MTBCFof about 115 kHrs and an operation availability of about 99.998% withoutput power reaching an ultra-high power level of 40 kW.

The disclosed architecture may make an ultra-high power SSHPA feasibleand its reliability superior to legacy radar transmitter technologies.The disclosed architecture may be suitable for mission critical highpower RF and microwave applications.

FIG. 2 is a simplified block diagram of an example of a 40 kW (9m+1n)combined high power amplifier (CHPA) with an interface control unit(ICU) 250 and other control components. A different number of “m” and“n” PAUs may instead be used. The CHPA may include an input powerdivider (DIV) 230 of the type discussed above, PAUs 201-210 of the typediscussed above, and a switching combiner unit (SCU) 220 of the typediscussed above.

The interface control unit (ICU) 250 may effectuate automatic fail-over.The PAUs 201 to 209 may be initially online and the PAU 210 may beinitially standby.

Each PAU may deliver 5 kW peak power and may include a PAU controller,such as PAU controllers 2012, 2022, 2032, 2042, 2052, 2062, 2072, 2082,2092, and 2102.

Each PAU controller may monitor one or more operating conditions of itsPAU that may be relevant to the operational status of the PAU, such asRF input to the PAU, RF output from the PAU, VSWRs, pulse width, pulseduty cycle, one or more temperatures, one or more voltages, and/or oneor more currents. Information about these monitored characteristics maybe delivered by each PAU controller to the interface control unit 250and/or another subsystem.

Each PAU controller may be able to make adjustments to its PAU based onone or more control signals from the interface control unit 250 and/orone or more other control signals, such as adjustments in the gainand/or phase of its PAU and/or a change in its online status. Each PAUcontroller may be able to provide protection, including protectionagainst over-voltage, over-current, over-temperature, over-pulse width,over-pulse duty cycle, and/or a high VSWR. These built-in shutdownprotections may prevent damage to the PAU when the PAU encountersvarious over-limit conditions.

The signal combiner unit 220 may include high power RF switches 2201 to2210. Initially, the RF switches 2201 to 2209 may be on (e.g., through)and the switch 2210 may be off (e.g., isolated). The outputs of the PAUs201-210 may be connected to the switching combiner unit 220 via highpower, matched cables 2901 to 2910. The summed 40 kW power output fromthe switching combiner unit 220 may be delivered through an outputcoupler 240 to an RF output port 22. The output coupler 240 may coupleCHPA forward power and reflected power to the ICU 250 to be detectedthereby to monitor CHPA operating status.

The interface control unit 250 may monitor the parametric status of allPAUs through their built-in PAU controllers and report this status tothe upper level control unit if needed via an I/O interface 23. Theoutput coupler 240 may sample forward and reflected signals and sendthese sampled signals to the interface control unit 250 as part of theCHPA status monitoring.

When a failure or out of specification condition is detected among anyof the monitored parameters during the amplification of an input signalby the PAU controller or the interface control unit 250, the interfacecontrol unit 250 may delay taking corrective action until the inputsignal ceases, such as after a pulse in a radar signal is finished, butbefore the next pulse begins.

For example, the interface control unit 250 may have determined that thePAU 201 has failed or is no longer operating within a specifiedparameter based on the report from the controller 2012. As soon as theinterface control unit 250 detects the cessation of the input signal oris advised of its completion by an acknowledge signal received over theinterface 23, the interface control unit 250 may place the failed PAU201 offline via its controller 2012, turn off its RF switch 2201 insidethe switching combiner unit 220, place the PAU 210 online via itscontroller 2102 to replace failed PAU 201, and turn on its RF switch2210 inside the switching combiner unit 220. This intra-pulse detectionand inter-pulse automatic fail-over scheme may avoid switching actionsduring the presence of a high power RF signals which otherwise mightcause a high power RF switch failure or other critical failure orproblem.

The automatic fail-over action may not interrupt power pulsetransmission, which might result in the delivery of a defect pulse with−1 dB lower power in the worst case. The RF switches in the switchingcombiner unit 220, such as the RF switch 2201, may provide a high degreeof isolation when off (e.g., isolated), thus preventing harmfulradiation from flowing back to the cabinet of a failed and offline PAU201 after it is physically removed from service.

The PAUs may each receive their input through a detachable blind mateinterface, such as through one of the TNC connectors 24. Similarly, thePAUs may each deliver their output through another detachable blind mateinterface, such as through one of the SC connectors 25. This may enableeach PAU to be easily detached and removed from the rest of the systemfor repair, testing, and/or replacement.

Positional sense switches 2701-2710 may each detect the presence oftheir respective PAU. When a PAU is fitted into its input TNC connector24 and output SC connector 25, its respective positional sense switchmay be configured and oriented to close. Conversely, When a PAU isdetached from its input TNC connector 24 and output SC connector 25, itsrespective positional sense switch may be configured and oriented toopen. The switch may be set to detect the detachment of a PAU after theremoval process begins, but before any electrical connection is broken.

The combined high power amplifier (CHPA) that is illustrated in FIG. 2may include input RF switches 2601 to 2610 that are connected to andcontrolled by their respective positional sense switches 2701 to 2710.The input RF switches 2601 to 2610 may be connected to their respectivePAU through matched connection cables 2801-2810.

Thus, the removal of a PAU from the CHPA may automatically stop itsinput signal from reaching its input TNC connector. Conversely, theinsertion of a PAU into the CHPA may cause its input signal to bedelivered to its input TNC connector. Thus, each PAU may be hotswappable.

FIG. 3 illustrates the mechanical layout of an example interface betweena PAU 301 (which may be of any of the types discussed above) and acombined input signal divider and switching combiner unit (DIV/SCU) 303including an input power divider/switching combiner unit (which may beany of the types discussed above). This interface may be used in theCHPAs illustrated in FIGS. 1 and 2.

This interface may include the male end of a slide-on blind mate TNCconnector 3013 and the male end of a high power slide-on blind mate SCconnector 3023 fastened to the exterior of the PAU 301, the male end ofa slide-on blind mate TNC connector 3011 and the male end of aslide-on-blind mate SC connector 3021 fastened to the exterior of thecombined DIV/SCU 303, and matched connecting TNC RF barrel 3012 and SCRF barrel 3022 proving an electrical connection between the shield andcentral conductor of their paired connectors, respectively. The SCconnectors may facilitate an output power of at least 5 kW peak power.This scheme may be used on each PAU.

The use of blind mate connectors may allow each PAU to be connected anddisconnected from the circuit with a simple sliding motion. A divided RFinput signal may thus propagate from a matched input cable 305 to theslide-on blind mate TNC connector 3011 on the exterior of the combinedDIV/SCU 303, then through the TNC RF barrel 3012 to the slide-on blindmate TNC connector 3013 on the exterior of the PAU 301, and then throughthe slide-on blind mate TNC connector 3013 to the PAU 301. The inputsignal may be amplified by the PAU 301 and then sent through the highpower slide-on blind mate SC connector 3023 on the exterior of the PAU301 through the SC RF barrel 3022, and then through the blind mateslide-on SC connector 3021 on the outside of the combined DIV/SCU 303.

The mating connectors and the positional sense switch associated witheach TNC connector may be configured such that: (1) electrical contactis made between both sets of mating connectors on the PAU 301 before theposition sense switch detects the connection; and (2) electrical contactis not broken between any set of mating connectors on the PAU 301 untilafter the position sense switch detects that the PAU 301 is beingdetached.

Each corresponding set of blind mate slide-on connectors may beconfigured to allow at least 25 mils of radial misalignment and at least60 mils of axial float. The position sense switches may be configured todetect a connection and disconnection when there are only 20 mils ofaxial separation. This may enable the interface control unit 250 todetect the removal of a PAU and to deactivate it before its electricalconnections are broken. This may similarly allow a PAU to be insertedinto an empty slot and for its electrical connections to be establishedbefore power is applied to the inserted PAU by the interface controlunit 250.

For example, when an online PAU is removed during operation, such as thePAU 201 in FIG. 2, the positional sense switch 2701 may sense theremoval before any electrical contact with the PAU has been broken, suchas when the displacement is greater than 20 mils from a nominalposition. The positional sense switch 2701 may send a control signal tothe input RF switch 2601 to isolate the RF input signal from the PAU201. Due to the lack of input signal to PAU 201, the PAU 201 may notprovide any output power. The absence of this output power may bedetected by the interface control unit 250 which may then deactivate thePAU that is being removed within no more than 100 μS following detectionof that removal by the input RF switch 2601. This is based on theassumption that it will take more than 100 μS for the PAU 201 to bemoved past the point of tripping the input RF switch 2601 until thefirst of its electrical connections with the circuit are broken.Deactivating the input to the PAU 201 and the PAU 201 before any of itselectrical connections with the circuit are broken may help insure thatthere is no high VSWR condition or arcing damaged caused by the removalof an online PAU 201, thus further facilitating hot swapping.

The TNC and SC blind mate slide-on connectors may each include a detentto hold their respective barrels in place, as shown in FIG. 33, duringremoval of the PAU 301. 33101 to 33110 are TNC barrels to the inputs of10 PAUs, and 33201 to 33210 are SC barrels to the outputs of 10 PAUs.

FIG. 4 illustrates an example of a prior art high power combinedamplifier that uses a conventional radial combiner 4020 with “n” inputs.The combined amplifier includes an input port 41, an input power divider4010, and PAUs 401-4N. The conventional radial combiner 4020 ties “n”50Ω input ports to a common port and transfers the (50/N) ohm impedanceto 50Ω output impedance. The coherent amplified RF signals are providedas inputs to the “n” input ports of the conventional radial combiner4020. All of the “n” RF signals travel through 50Ω lines with equallength L, join at the geometric center node “C,” and are coherent.Hence, the impedance of node “C” is 50Ω/N. An impedance transformer 4021has an impedance Z1 expressed in equation 8 and a λ/4 electrical length:

$\begin{matrix}{{Z\; 1} = \frac{50\; \Omega}{\sqrt{N}}} & (8)\end{matrix}$

and will transfer the (50/N)Ω impedance to a 50Ω output impedance at anoutput port 42. More than one step transformer may be used to increasebandwidth.

The conventional radial combiner 4020 may not have sufficientport-to-port isolation to allow a high power or ultra-high power outputcombiner to operate safely with a failed PAU at one of its ports for anyperiod of time. When a single PAU fails, such as PAU 401, the totalpower loss at the output port 42 may exceed 2/N times the nominal power.Due to the VSWR effects of operating the high power radial combiner withjust a single failed PAU in one port, the mismatch may cause powerreflections that may damage the combiner and all of the other operatingPAUs over time.

This may be especially true in the case of a “short” failure located ata multiple of a 180° electrical length from node “C.” The “short” mayparallel with 50Ω/(N−1) to create near 0Ω impedance at “C.” Then, nearly100% of the output power may be reflected back to all of the PAUs. Thismay well cause a catastrophic failure.

When a PAU is physically removed, the corresponding input port of thecombiner may be left un-terminated or un-isolated, so that all of theother PAUs may contribute significant power to the total of (N−1)/N ofPAU outputs at the open port. Thus, the large harmful radiation may alsobe present if one of the PAUs is physically removed while in thetransmit mode. Under such conditions, the CHPA with a conventionalradial combiner may not meet standards for EMI/EMC compliance and safetyregulations, at a minimum. Even worse, when the open port is located atan odd number of quarter wavelengths from the node C, the effective near0Ω impedance at “C” may cause catastrophic failure.

This entire system may need to be shut down while each failed PAU isreplaced. But this may result in an extremely low operationavailability. So making an ultra-high power CHPA with a conventionalradial combiner may not be a viable solution.

The practical MTBFs for the PAUs, DIVs, and radial COMs that have beendescribed may be at least 50 kHrs, 500 kHrs, and 150 kHrs, respectively.Then, the MTBCF of a conventional CHPA including 10 PAUs may be lessthan 5 kHrs.

FIG. 5 illustrates an example of a switching combiner unit (SCU) circuitthat can automatically and safely disconnect an input port in responseto a shutdown command, such as a shutdown command from an interfacecontrol unit, such as the interface control unit 250 in FIG. 2. Such anSCU may be used as the SCU 111 in FIG. 1 and/or the SCU 220 illustratedin FIG. 2.

The SCU illustrated in FIG. 5 may include high power RF switches to allinput ports among which “m” ports are initially switched on and “n”ports are initially switched off. Thus, the SCU introduces redundancy tothe combining scheme. When a PAU to one of “m” on ports fails, its portmay be switched off (isolated) and one of “n” ports may be switched onat about the same time so that the output impedance and output power mayremain unchanged.

High power PIN diode RF switches 5013-5(m+n)3 may be used as theswitches. However, any other type of switch may be used instead, such asa FET, bipolar transistor, mechanical switch, or electro-mechanicalswitch.

In an initial default mode, the coherent high power RF signals from “m”online PAUs may be input to 500 input ports 501 to 5 m.

The switching functionality associated with the first input port 501will now be explained. The same explanation applies to the other inputports and their associated −V control inputs 5026 to 5(m+n)6, +V controlinputs 5017 to 5(m+n)7, capacitors 5025 to 5(m+n)5, 5021 to 5(m+n)1, and5022 to 5(m+n)2, inductors 5024 to 5(m+n)5, and transmission lines 5202to 52(m+n).

The RF signal from the input port 501 may propagate through two blockingcapacitors 5011 and 5012, between which the high power PIN diode 5013may shunt between the RF line and ground. A reverse voltage −V at a −Vcontrol input 5016 may be filtered by a capacitor 5015 and passedthrough an RF coil 5014 and then to the PIN diode 5013, causing aneffective resistance of the PIN diode 5013 to be in the tens ofthousands of ohms. Thus, the RF insertion loss due to the addition ofthe PIN diode may be negligible.

All “m” signals through identical RF switches and transmission lines5201 to 52m with Z1 impedance and λ/4 electrical length may merge at thecenter C of the radial shape SCU, at which the “n” off ports alsointercept. For the initially off input ports, a forward voltage +V maybe applied at +V control inputs 5(m+1)7 to 5(m+n)7. This may cause theeffective resistance of the PIN diodes 5(m+1)3 to 5(m+n)3 to be about0.25Ω. The 0.25Ω low impedance in the places of forward biased diodesmay be transferred to near 10 kΩ at node “C” when Z1=50Ω. Theparalleling effect from “n” number of nearly 10 kΩ resistors at “C” maybe insignificant. Thus, the forward biased diodes may isolate theirrespective input ports from the common junction “C.”

The selection of Z0 may be associated with the default “m” and operationbandwidth. With a large “m” value and a broad bandwidth requirement,making Z0 greater than 50Ω may increase the impedance Z0/x at node “C.”This may ease the impedance transformation by transformer 5301 with Z2impedance and λ/4 electrical length. The multiple sections of quarterwavelength lines may be implemented at Z2 line to increase thebandwidth. When an (m+n)SCU is designed to operate at optimal powerdelivery at an output 5001 to 50Ω, the random parameter x in node “C”may be “m” to achieve the best VSWR (theoretically 1:1) with “m” PAUsonline. Even with (n+1) failed PAUs and (m−1) PAUs online, the SCUpresents {m/(m−1)}50Ω, instead of 50Ω nominally with <n failed PAUs.

The larger “m” is, the closer SCU output impedance may be to 50Ω. Forexample, for m=9, the VSWR of SCU may be 1.125:1 when 8 ports are on.Therefore, graceful degradation may be achieved with outstandingcombining efficiency. On the other hand, more than “m” ports of the(m+n)SCU can be placed “on” in order to achieve higher than nominalpower delivery. Thus, the disclosed (m+n)SCU may be flexible so that itcan be implemented in various applications.

Table 2 below demonstrates the effect on (m+n)SCU VSWR with differentnumbers of online PAUs and (9+1)SCU.

TABLE 2 (m + n)SCU VSWR with different numbers of online PAUs and (9 +1)SCU (m + n)SCU Optimized (9 + 1)SCU Optimized for “m” PAUs for 9 PAUsoperation # # Power Output “online” Output “online” Loss Power PAUs VSWRPAUs VSWR (dB) (%) m + 1 (m + 1)/m 10 1.11:1 −0.012 110.8%  m 1:1 9  1:1 0.00  100% m − 1 m/(m − 1) 8 1.13:1 −0.016 88.5% m − 2 m/(m − 2) 71.29:1 −0.07 76.5% m − 3 m/(m − 3) 6 1.50:1 −0.18  64%

Note that, in the (9+1)SCU example, the SCU may present excellent 1.29:1VSWR and −0.07 dB transmitted power loss due to mismatch with 7 PAUsonline or 3 failed PAUs. If more than 3 ports are “off,” the (9+1)SCUmay show 1.50:1 VSWR and −0.18 dB power loss which may be undesirable.In this case, the entire SCU can be programmed to be shut down by itsinterface control unit. As suggested by this last sentence, the variousswitching control signals that have been described may originate from aninterface control unit, such as the interface control unit 250 shown inFIG. 2.

The parameter x can also be optimized by considering that (m+n)SCU maysupport nominal y PAUs online, graceful degradation with y−1 PAUsonline, and high power mode and high power operation with y+1 PAUsonline. Then,

X=√{square root over ((y−1)(y+1))}{square root over ((y−1)(y+1))}  (9)

The corresponding VSWR for (y−1) ports on and (y+1) ports on may be thesame as equation 10, so symmetric VSWR performance can be achieved:

VSWR=√{square root over ((y+1)/(y−1))}{square root over((y+1)/(y−1))}  (10)

If y=8 in (9+1)SCU, then x=7.937. Therefore, the SCU VSWR may be 1.134:1for 9 and 7 PAUs online, while 1.007:1 for 8 PAUs operation. The optimaldesign approach may be subject to specific application requirements.

FIG. 6A illustrates an exploded view of an example of a switchingcombiner unit (SCU); FIG. 6B illustrates an enlarged view of a portsection of the switching combiner unit; and FIG. 6C illustrates theswitching combiner unit fully assembled. This SCU may be used as the SCU111 in FIG. 1 or the SCU 220 in FIG. 2. The SCU in FIGS. 6A-6C maycontain the circuit illustrated in FIG. 5.

The SCU may be configured for 9 initially online PAUs and 1 initiallystandby PAU (a (9+1)SCU) that can deliver more than 40 kW peak powerwith nominal 9 ports on, each of which may receive about 5 kW nominalpeak power operating at 3.8% nominally and up to 6% maximum duty cycleunder pulsed condition for an approximately 900 MHz radar application.Right angle SC connector RF input ports 601 to 610 may be capable ofhandling more than 5 kW peak power, and 500 output port 611 may be a7/16 DIN connector specially designed to handle more than 40 kW peakpower.

Each of the ten input circuit branches may have a uniform layoutconsistent with a conventional radial combiner, with a center node 613being low impedance. The impedance transformations from the center node613 to the 500 output port 611 may be implemented by two sections ofimpedance transformations. One may be a strip-line transformer 614 andanother may be a coaxial transformer 615.

Each of the input ports may be associated with PIN diode switchingcircuitry of the type discussed above in connection with FIG. 5.Multiple diodes may be implemented to increase switching isolation.

A high power RF switch 6011 utilizing PIN diodes may be separated by aλ/4 transmission line impedance transformer 6012 from the center node613. A reverse voltage applied to the diode through an interface Sub-Dconnector 612 may place the PIN diode switch on, and a forward voltagemay turn the input port 601 off. The same may apply to the switchingcircuits for the other ports.

A distribution board interface 616 may be between the Sub-D connector612 and the ten RF switches. +V/−V bias may be supplied via the Sub-Dconnector 612 and may be distributed via the distribution boardinterface 616 to the location of its corresponding diodes.

In another embodiment, a high isolation passive input power dividerdesign may have the symmetric splitting circuitry like the one in radialcombiner and built-in terminations that divide the input signaluniformly and absorb the reflected signal due to the output portmismatch. The built-in terminators to each output port may independentlyabsorb the reflected signal from its corresponding port and may notsuperimposition to other output ports. This may be superior to a radialdivider which may have no port-to-port isolation and to a Wilkinsondivider which may have poor port-to-port isolation.

FIG. 7 is a schematic of an example of an N-way input power divider(DIV) that may provide high port-to-port isolation. This divider may beused as the divider 109 in FIG. 1 or the divider 230 in FIG. 2.

An input RF signal may enter an input port 71 and travel through a Z0transmission line 72. The input signal may then be divided into “n” waysequally at junction 73. The divided input signals may propagate to theirrespective output ports 701 to 7N. In addition, the signal at a junction7012 may travel through a Z2 λ/4 transmission line 7013 with a −270°phase at a junction 7014, so is the signal −270° phase at 7024.

The forward signal at the 50Ω load 7015 may continue its path through aZ3 λ/4 transmission line 7016 and a Z3 λ/4 transmission line 7026 to a500 load 7025 with −450° phase. That is to say, there is a forwardsignal from 7023 and a reverse signal from the transmission line 7013with Δφ=−180° at the 50Ω load 7025. Thus, the 50Ω loads 7015 to 7N5 arevirtual grounds to the output ports 701 to 7N. The 0Ω virtual ground istransformed to near infinite high impedance at the junctions 7012 to7N2. Therefore, the N-way divider, from input port 71 input to outputports 701 to 7N can be designed following conventional radial combinerdesign rules, as in FIG. 4, except that L=λ/4.

Assume that there is a reflected signal inputted at an output port 703,due to a mismatch at the output port 703. The signal may travel throughthe Z2/50Ω transmission line 7033 to a 50Ω load 7035. In addition, thesignal may travel through a Z1 transmission line 7031 and a Z3transmission line 7036, the phase changes for reflected signal paths arenoted (RFL). The two signals may eventually meet at an output port, suchas the output port 702, with Δφ=−180° phase and cancel each other.Therefore, the signal input from one output port, such as the outputport 703, will not be present at any other output port, such as theoutput port 702. Thus, outstanding port-to-port isolation may beachieved.

The circuit illustrated in FIG. 7 may provide more than a 12% bandwidtharound the center frequency. Other wideband features may be added. Forexample, a λ/4 transmission line or multiple parallel higher impedancelines may be added at the junction 73. A series tuned LC circuit,including L7N and C7N, may in addition or instead be added at the inputof the built-in 50Ω load. A −180° series circuit can be implementedusing a λ/2 Z4 transmission line 7N7. Optional broadband circuits may beincluded, as illustrated in dash boxes at the bottom of FIG. 7 and mayimprove the bandwidth by more than 28% from the center frequency.

FIG. 8A is an exploded view of an example of a 10-way input powerdivider; FIG. 8B illustrates an enlarged view of a portion of a PCBwithin the divider; FIG. 8C illustrates a rear view of certaincomponents of the divider; and FIG. 8D illustrates the divider fullyassembled. The figures illustrate various transmission lines andbuilt-in terminators using two PCB assemblies interconnected via SMP RFconnectors. This divider may be used as the divider 109 in FIG. 1 or thedivider 230 in FIG. 2. This divider may contain the circuit illustratedin FIG. 7.

The divider may operate within a band from 800 MHz to 1000 MHz.

An input connector 81 and output connectors 801 to 810 may be TNC, whichmay be adequate to handle 100 W peak power. A λ/4 coaxial transmissionline 82, like the transmission line 72 in FIG. 7, may transform 500 atthe input connector 81 into a low impedance at a center hole 83, whereall ten identical branches may merge. All of the transmission lines inFIG. 7 may be laid out on two multilayer PCBs 8302 and 8304, which maybe enclosed by a housing 8301, a partition plate 8303, a gasket 8305,and a lid 8306. The two multi-layer PCBs 8302 and 8304 may have SMPconnectors, such as SMP connectors 84012 and 84013, which may beinterconnected via SMP barrels, such as SMP barrel 84011. Built-interminators, such as built-in terminator 84014, may be mounted on thePCB 8304.

FIG. 8B illustrates an exploded view of one of what may be ten identicalcircuits from input connector 81 to output connector 801. It illustratestransmission line design details, specifically transmission lines Z1,Z01, Z2, Z3, and Z4, which may be the same as the corresponding ones inFIG. 7. The signal at the center hole 83 of the PCB 8302 may go throughthe transmission line Z1 and then through a 500 line to the outputconnector 801. The joint of Z1 line and 500 line may be interconnectedthrough vias and SMP connectors and a barrow to the multi-layer PCB8304.

The broadband λ/4 transmission lines Z01 may be laid out in the PCB8302. However, a total of ten of transmission lines Z01 may beimplemented so that each individual line can provide a higher impedancewith a narrow trace width. The SMP connector 84012 on the PCB 8304 maygo to the λ/4 transmission line Z2, and the vias may continue itscircuitry to the far side of PCB 8304 illustrated in FIG. 8C. The Z3 λ/4transmission line, connecting the end of Z2, may merge with the othernine identical lines at the center. In another path, the λ/2transmission line Z4 may connect the end of Z2 and may go to the 500terminator 84014.

The λ/2 transmission line Z4 broadband technique may be implemented inthe example 10-way divider design. The example divider may providegreater than 28% bandwidth centered at 900 MHz.

In another embodiment, a high density SSHPA design (PAU) may reduceoverall profile and increase overall power density. A T-Plate structuremay be used with three significant planes—two opposite horizontal planesto mount power devices and one vertical plane to interface to a coolingplate. The structure may double power density as compared to aconventional layout architecture, minimizing the power amplifierprofile. The power amplifier architecture may embed high thermalconductive material between the two horizontal surfaces. This mayeffectively transfer their heat onto the vertical plane to interfacewith the cooling plate. The approach addresses heat transfer issues thatall power amplifiers face.

FIG. 9 is a block diagram of an example of a 5 kW compact pulse radarpower amplifier with monitor, control, and protection features operatingin low L-Band. An RF signal of around 5 W may be injected to an inputmodule 901 via an RF input connector 960. The signal may be boosted byamplifiers 951 and 952 and equally divided through a driver/dividermodule 950 and delivered to four basic amplifier modules (BAM) 910, 920,930, and 940.

Each BAM may include multiple power devices, such as amplifiers 911 and912 in BAM 910, amplifiers 921 and 922 in BAM 920, amplifiers 931 and932 in BAM 930, and amplifiers 941 and 942 in BAM 940 that may eachdeliver about 700 W peak power and generate significant heat with around50% efficiency. Each BAM may also include a bias and control module thatenables or disables the power device, such as bias and control modules913, 923, 933, and 943. An output module 902 may sum the four BAMoutputs, each delivering greater than 1.25 kW into 5 kW output power atan output 970.

There may also be capacitor banks 903 and 904 that store adequate energyto meet pulse operation needs. An interlock 905 may relay DC input Vdsto the power devices after ensuring the power pin mate to avoid archingcaused by the large inrush current. A DC power distribution module 906may generate +5V, +3.3V, +20V, −4.1V from input +50V and distributes tothe sub-assemblies. A detection module 907 may detect RF input/outputand reflected RF at the output. And a controller 908 interfacing via aconnector 980 may monitor parameters detected in various sub-assembliesand control the input module 901, interlock 905, and BAMs 910 to 940.

Due to relatively large dimensions of the power devices, such as1.3″×0.4″ each, and other bulky modules, a conventional single surfacelayout scheme may make it difficult to implement such a system in asmall space to deliver hundreds of kW to replace a Klystron radartransmitter.

FIG. 10 illustrates an example of a T-plate structure that may be usedto compactly contain and cool the components in the compact pulse radarpower amplifier shown in FIG. 2. The T-plate structure may include ahorizontal plate 1001 and a vertical plate 1002. The horizontal platemay offer two significant planes on which to mount multiple powerdevices, such as four on each side, such as the four devices 1011 on thevisible side in the drawing.

The vertical plate 1002 may provide thermal removal. The vertical plate1002 may thermally interface with a water cooling plate 1004 viathermally-conductive interface material 1003. Cooling water or otherfluids may be injected in water inlet 1021 and exit after removing heatfrom water outlet 1022. Cut-outs, such as cut-outs 1031, may be providedto embed bias control modules to minimize the high power interferenceand to effectively utilize available space that is not in the thermalpath.

This T-plate structure may reduce the horizontal surface area by about50% while, at the same time, doubling the amount of heat per unit areathat can be managed. The plates of the T-plate structure may be of anythermally-conductive material, such as metals like Al or Cu. The platesmay be part of a unified structure or may be separate pieces thermallyconnected, such as through brazing or soldering.

Power device junction temperature may determine whether a poweramplifier based on a T-plate structure can meet a reliabilityrequirement. The higher the device output power, the greater may be thechallenge of removing heat from the devices to the vertical plate 1002.

FIG. 11 illustrates an example of high thermally-conductivity material1101, 1102, and 1103 that may be embedded in the thermal path of aT-plate structure to improve thermal conductivity. The material may bebrazed or welded. The material may be of any type, such as copper or agraphite-based material that offers significantly higher thermalconductivity, such as 398 W/k-m or 1500 W/k-m, without increasing theweight dramatically, as compared to conventional aluminum with 167W/k-m.

FIG. 12 is an example of a thermal model for the T-plate structureillustrated in FIGS. 10 and 11. The model illustrates all thermalresistances from the bases of the heat-generating devices to the coolingwater. The model includes temperatures at junctions 1210, 1220, 1230,1240, 1250, 1260, 1270, 1280 of the power devices, each of which maynominally generate an average heat of about 25 W. The model alsoincludes junction-to-case thermal resistances 1211, 1221, 1231, 1241,1251, 1261, 1271, and 1281. The model also includes temperatures at theflanges of power devices, like those on the BAMs in FIG. 9, namelyflanges 1212, 1222, 1232, 1242, 1252, 1262, 1272, and 1282. The modelalso include the case-to-horizontal surface thermal resistances 1213,1223, 1233, 1243, 1253, 1263, 1273, and 1283.

The junction 1201 represents the temperature at the device center linebetween devices on two parallel horizontal surfaces. The thermalresistance 1202 represents thermal resistance from the center line ofthe devices to the T-plate joint, represented by junction 1203. This maybe the most critical resistance due to a total thermal path (longesttraveling distance) of about 1.9″ in the example. The thermal resistor1204 represents cooling plate resistance from the interface to thecooling liquid. For the 1202 thermal resistance,

$\begin{matrix}{R = \frac{L}{KA}} & (11)\end{matrix}$

where L is the travelling distance of the generated heat in (m), A isthe cross area in (m²) of the thermal media, and K is the thermalconductivity in (W/m−K). The embedded material's effective dimensions inthe example are L=1.9″ W=5.6″, H=0.225″,

L=1.9″=0.04826(m)  (12)

A=5.6*0.225(in²)=0.0008(m²)  (13)

So,

$\begin{matrix}{R = {\frac{60.325}{K}\left( {}^{{^\circ}}{C\text{/}W} \right)}} & (14)\end{matrix}$

In the example amplifier, the embedded material may be a graphite-basedmaterial that has 1500 W/m-K thermal conductivity.

R _(Graphite)=0.04(° C./W)  (15)

The temperature increase through 1.9″ distance with total of 197 W heat

ΔT _(Graphite)=7.88(° C.)  (16)

The following table sets forth characteristics of various materials,including Al and Cu, with 167 (W/m-K) and 398 (W/m-K) conductivity,respectively:

K R ΔT (° C.) @ D Parameter (W/m-K) (° C./W) 197 W Heat (g/cc) GraphiteBased Material 1500 0.04 7.88 2.26 Cu -110 Alloy 398 0.15 29.86 8.326061-T6 167 0.36 70.92 2.79

The thermal removal capacity of graphite-based material may be superiorto Cu and Al, such as 3.8 times better than Cu and 9 times that of Al.Its weight may be lighter than Al and may be significantly lighter thanCu (3.7 times lighter). The detailed material selection may be dominatedby specific amplifier requirements, including reliability. In theexample amplifier with 197 W average heat, the 22° C. junctiontemperature improvement from graphite-based material to Cu alloy maydouble the reliability of the power devices.

When using a T-plate structure, all power devices may be laid onto twohorizontal planes symmetrically to achieve uniform thermalcharacteristics among them. The divider/driver module 950 and the outputmodule 902 in FIG. 9 may be configured to interface horizontally withthe basic amplifier modules 910, 920, 930, and 940 with minimum spaceoccupied and interconnection power losses. Details are shown in FIGS.13, 14, 15, and 16.

FIG. 13 illustrates an example of a layout 1306 that may be use for eachbasic amplifier module (BAM). The layout is for two power devices 1301and 1302. The layout 1306 may be constructed with minimum thermalresistances and with a horizontal input port 1310 and an output port1320. To minimize thermal resistance, the power devices 1301 and 1302may be soldered to a carrier 1308. Space saving baluns 1303 using 0.047″OD coax and 1304 using 0.086″ OD coax may be in a combining scheme toshorten the thermal path. The bias and control modules 913, 923, 933,and 943, shown in FIG. 9 as module 1307, may be embedded underneath theinput matching layout to further minimize size and to shield out highpower interference, with connector 1330 interfacing with the DC powerdistribution module 906. Temperature sensors 1331, 1332, and 1333, maybe mounted under the power devices 1301 and 1302 and the carrier 1308,and may report device and base plate temperatures.

FIG. 14 is an example of a compact high power combiner module with RFinterfaces perpendicular to the layout plane and which may also provideforward/reflected power coupling functions. The output module 902 inFIG. 9 may include a 4-way combiner and directional coupler, configuredas shown in FIG. 14. Input ports 1401, 1402, 1403, and 1404 may beperpendicular to the circuit layout plane so that they can directlyinterface with 4 BAMs, without cabling to minimize power loss and space,as shown in FIGS. 16A and 16B.

FIG. 15 is an example of a compact driver/divider with RF interfacesperpendicular to layout plane, and includes DC distribution, controls,driver amplification, and divider circuitry. It may use the same designapproach as used in the driver/divider module 950 and the DC powerdistribution module 906 in FIG. 9. RF ports 1501, 1502, 1503, and 1504may directly interface with BAM input ports. The connectors 1506 and1507 may directly interface with bias and control modules providing biasand enable to the BAMs and receive temperature monitor signals fromBAMs. The divider may also include RF input 1505 and DC input 1508.

FIGS. 16A and 16B are an example of different views of direct interfaces1611 and 1612 between a driver divider module 1610 and BAMs 1630 and1640, as well as direct interfaces 1621 and 1622 between output module1620 and BAMs 1630 and 1640. Each BAM, like BAM 1630 or 1640, mayamplify its input and delivers 1.25 kW to the combiner 1620.

FIG. 17 is an exploded view of an example of a 5 kW compact high poweramplifier that uses a T-plate structure in a compact design. This designmay provide great space-saving advantages. An input module 1701 may beattached to a vertical plate. Capacitor banks 1703 and 1704 may directlyinterface with BAMs, an interlock module 1705, a DC distribution module1706, a detector module 1707, and a controller module 1708 utilizing aT-plate structure.

FIG. 18 illustrates an example of a solid state amplifier, a coolingplate 1803, and a single bolt 1801 that may be used to easily attachedand detach them from one another. In addition to utilizing spaceeffectively, the T-plate structure may minimize the vertical planesurface area, thereby allowing the single bolt 1801 to attach the solidstate amplifier to the cooling plate. The single bolt 1801 may be ¼″-20and may provide significantly more than 700 lbs clamping force toseamlessly attach a vertical plate 1802 of the amplifier to the coolingplate 1803 to ensure minimal thermal resistance. Blind mate connectorsmay be used for RF input 1810, RF output 1820, and DC/interface 1830,thus allowing the amplifier to be hot swappable.

FIG. 19 illustrates an example of a fully assembled 5 kW compact highpower amplifier utilizing a T-plate structure. The amplifier may operatewith a nominal duty cycle of 3.8% and up to 6% under pulsed conditionsfor radar applications. The amplifier may include parametric monitors,including RF in, RF out, VSWRs, temperatures, voltages, and currents.The amplifier may provide adjustments, such as for gain and phase, andinclude online and standby controls, and protections that may includeover-voltage, over-current, over-temperature, and high VSWR. Theamplifier architecture may enable a high power HPA with near 40 W/in³power density and hot swapping using a ratchet 1901 accessible from itsfront face.

Features of the T-plate structure may include:

-   -   A solid state amplifier (SSA) may utilize a T-plate structure        that includes three significant planes, with two opposite        horizontal planes each having power devices mounted on them, and        one vertical plane to interface with a cooling plate for the        removal of heat with the heat traveling from the        power-generating devices to the vertical plate.    -   Material with high thermal conductivity may be embedded between        the horizontal planes in the thermal propagation path to        minimize the thermal resistance.    -   A solid state amplifier may utilize multiple power transistors        to achieve high power with high power density and may include        multiple basic amplifier modules (BAM). Each BAM may provide        mounting for more than one power transistor.    -   A solid state amplifier may combine multiple BAMs and utilize an        output combiner module with input ports perpendicular to the        combiner layout to save space and to minimize the loss.    -   A solid state amplifier may combine multiple BAMs and utilize an        input divider module with output ports perpendicular to the        divider layout to save space and to minimize the loss.    -   A solid state amplifier may provide various functional blocks        that can be integrated surrounding the T-plate structure using a        space-saving layout to minimize the SSA profile.    -   The vertical plate may have a small profile so that a single        bolt may be used to attach the SSA to the cooling plate.    -   Blind mate RF and DC interface connectors may be used to provide        a hot-swappable function.

In yet another embodiment, the liquid cooling system may further reducethe profile of the (m+n)CHPA and thus increase its power density.

FIG. 20 is an example of a water cooling system for an example(9+1)CHPA, showing liquid cooling distribution from an inlet to tenparallel cooling plates for ten PAUs. Each cooling plate may remove heatfrom its corresponding PAU independently. The water may flow with anominal 3.625 GPM rate and 30 psi pressure through a water manifold 2013via a water inlet 2011. The water manifold 2013 may split the water flowequally between input manifolds 2017 and 2015 and cause very littlepressure drop, such as only 0.44 psi. The input manifolds 2017 and 2015may be identical and each structured so that a 1.8125 GPM flow isuniformly split into five 0.3625 GPM outputs with negligible pressuredrop. All ten cooling plates 2001 to 2010 may be parallel to one anotherso that a specific PAU's thermal behavior will not be affected byothers. The cooling plates may be vacuum-brazed with machined fins onbase technology with a 6″×1.25″ effective thermal removal area. This mayensure 0.3625 GPM to adequately remove the heat from a 5 kW PAU with˜40% power efficiency at a maximum duty cycle, as shown in FIG. 19.Manifolds 2016 and 2014 may be symmetrical to input manifolds 2017 and2015, respectively, to regulate the return water to the water manifold2013 and then exiting a water outlet 2018.

FIG. 21A illustrates an example of a water cooling system for a(9+1)CHPA that includes manifolds 2114-2117 and cooling platesCP01-CP10. Manifolds 2114-2117 may distribute cooling water equally tothe ten cooling plates CP01 to CP10. The cross surface dimensions ofCP01 may be the same as those in the PAU shown in FIG. 19

FIG. 21B illustrates an example of the cooling plates CP01 illustratedin FIG. 21A and shows how PAUs may electrically interface with a DIV/COMassembly, power supply bank (PSB), and interface control unit (ICU). Theothers may be the same. Bellows 21011 and 21012 may connect the manifoldand the cooling plate, while providing various tolerances in the PAUsand the CHPA card cage assembly. Through holes 21013 and 21014 may befor barrels (like RF barrels 3012 and 3022 in FIG. 3) on the DIV/SCUassembly to penetrate and mate with PAU's RF input and output ports. Amicro-D connector 21016 on the far side may mate with the one on a PAUto supply +50V from a PSB via a cable 21017, and to communicate with anICU via a cable 21018. When the shaft of a PAU attaches the PAU to thecooling plate with >30 in/lb torque, the position switch in acompartment 21015 may send its control signal to its RF switch, such asto RF switch 2601 in FIG. 2, via a pin 21019.

FIGS. 22A and 22B illustrate different views of an example of a compact,modular 40 kW (9+1)CHPA with electrical and thermal interfaces.Electrical and thermal interfaces are identified in FIGS. 22A and 22B.They may include a TNC RF input 2221, a 7/16 DIN RF output 2222specially designed to handle 40 kW peak power, an RJ-45 Ethernetinterface 2223, a water inlet 2224, and a water outlet 2225.

FIG. 23 illustrates a cut-away and partially exploded view of the CHPAillustrated in FIGS. 21A and 21B and illustrates the integration ofmultiple assemblies, like PAUs, a cooling assembly, a DIV/SCU assembly,and an ICU assembly.

This (9+1)CHPA may reliably deliver 40 kW peak power. Multiple(m+n)CHPAs can be conventionally combined to provide a >100 s kW peakpower scalable solid state coherent radar transmitter, while stillproviding outstanding SSTx reliability and life cycle.

DC supplies to the CHPA assembly (not shown in these figures) may beprovided. The CHPA card cage assembly may enclose PAU assembly 2301 with10 PAUs in the front, a water cooling assembly 2302 to which the PAUsmay be attached, a divider/switching combiner unit assembly (DIV/SCU)2303 which may be interconnected with the PAUs via 10 pairs of TNCbarrels and SC barrels, each like 2361 and 2362, respectively, and anICU 2304 in the back.

The following Table 3 illustrates possible major performances of theexample (9+1)CHPA utilizing the configuration that has been discussed.

TABLE 3 Specifications for the (9 + 1)CHPA that may be achievedParameter Value Comments 1. Electrical Performance .1 Operating 850-942MHZ Minimum, Upper and Frequency Lower −1 dB Point .2 RF Output Power,75.64 dBm/ Min/Max, peak 76.64 dBm 36.6 kW/46.1 kW; 1 dB Variation .3 RFInput Power, 49.0 dBm (80 W) Nominal, +/−0.5 dB peak .4 Spurious Output60 dBc Minimum, from 962-1212 MHz .5 Harmonic Output 30 dBc 2nd, 40 dBcMinimum 3rd-5th .6 Input/output 1.5:1 Maximum VSWR .7 Output VSWR 2:1Minimum, all phase Survival .8 Pulse Width 2-64 μsec AV1: 32 uS max;AV2: 50 uS max .9 Pulse Duty Factor 6% Max, AV1: 3.87% max; AV2: 4.5%max .10 Rise/Fall Time 0.08-0.8 μsec 10% to 90% Power Point; 90% to 10%Point .11 Pulse Droop 0.25 dB Maximum, 10% to 90% time of 32 μsec Pulse.12 Pulse Phase 6 degrees Maximum, from 5 μsec Variation after leadingedge to 5 μsec prior falling edge with 32 μsec Pulse .13 Pulse Phase0.03 degrees RMS Maximum Stability .14 Pulse Amplitude 0.01 dB RMSMaximum Stability .15 Power Efficiency 40% Minimum .16 Primary Power 4.8kW at 50 VDC Maximum in AV2 Operation 2. Physical Parameter .1 Outline30″(L) × Nominal Dimensions 14″(W) × 14″(H) .2 Weight 100 lb Nominal .3Connectors TNC In, 7/16 Out, Ethernet 3. Thermal Parameter .1 WaterInlet/Outlet ¾″ ID Connectors .2 Flow Rates 3.625 GPM Nominal .3 Inlet43.3° C./50 psi Maximum Temp/Pressure

The (9+1)CHPA may be used as an SPS-49 Radar Transmitter. Thedemonstrated pulse quality may include pulse droop, pulse variation, andpulse-to-pulse stability superior to legacy Klystron technology. Thisoutstanding pulse quality inherent in solid state technology and circuitdesigns may be essential to achieve high Radar resolution.

In legacy radar transmitters utilizing Klystron and TWT technologies,the power supply may be designed to provide about a kV of DC with tubetechnology to the amplifiers achieving ultra-high RF power. LikeKlystron and TWT, legacy power supply technologies may face significantand increasing challenges of diminishing manufacturing sources, unstableoutput, and inherent low MTBF. The high voltage operation may alsoimpose safety issues for operators.

The introduction of solid state RF power device technology into HPAoperating typically with only tens of volts may be safer. In recentyears, switching solid state power technology has advanced rapidly up to5 kW with a small profile. The new switching technology, operating withtens of volts output, may provide a more stable DC output and a lowripple voltage of only tens of mV, which may be essential for obtainingoutstanding pulse-to-pulse stability for coherent pulse radartransmitter.

High voltage GaN technology has been introduced to switching powersupply design. This may significantly extend the reliability of thepower supply. In connection with an SPS-49 radar platform, the powersupply unit (PSU) may be designed around a 2.75 kW power supply with 440VAC 3φ input and 50 VDC output. Its calculated MTBF may be greater than100 kHrs in naval under deck environments.

However, in order to support hundreds of kW RF peak power, nearly 100power supplies may be needed. These may collectively provide areliability of less than 1 kHr MTBCF for the power supply system. Powersupply redundancy may be used to address this concern.

FIG. 24 illustrates a redundant (m+n) power supply bank ((m+n)PSB),along with an (m+n)CHPA of any of the types discussed above. Thearchitecture may have the same amount of power supply units (PSUs) asthe PAUs, with a one PSU-to-one-PAU scheme. All PSUs may be “on” withtheir DC outputs DC OUT present. “M” PSUs may be “online” due to “m”“online” PAUs drawing current. “n” PSUs may be in “standby” due to “n”“standby” PAUs not drawing current. When one of the “online” PSUs fails,its controller may send fault signals to the ICU (not shown in FIG. 24)and the ICU may place the corresponding PAU offline. Thus, the failedPSU may not supply the current to the offline PAU, so that the failedPSU may be offline instantly. Then, one of the “standby” PSUs mayautomatically fail over due to its corresponding PAU automatically beingplaced “online” by the ICU.

Therefore, automatic fail-over and uninterrupted operation of an(m+n)PSB may be achieved via its (m+n)CHPA. Then, the MTBF of the PSUsmay be excluded from the MTBCF calculation of the SSTx system consistingof one pair of an (m+n)CHPA and an (m+n)PSB. Thus, the introduction ofan (m+n)PSB architecture may not result in the SSTx MTBCF andavailability (Ao) degradations as shown in Equations 17 and 18.

$\begin{matrix}{{MTBCF}_{SSTX} = \frac{{MTBF}_{DIV}{MTBF}_{SCU}}{{MTBF}_{DIV} + {MTBF}_{SCU}}} & (17) \\{A_{OSSTX} = {\left\{ \frac{{MTBF}_{DIV} - {MTR}_{DIV}}{{MTBF}_{DIV}} \right\} \left\{ \frac{{MTBF}_{SCU} - {MTR}_{SCU}}{{MTBF}_{SCU}} \right\}}} & (18)\end{matrix}$

In addition, the graceful degradation feature with more than “n” PSUfailures and “hot-swap” feature may also be achieved as described abovein connection with an (m+n)CHPA.

In FIG. 24, PSUs 2401 to 24(m+n) are added to the basic (m+n)CHPA blockdiagram. The hatched PSU(m+1) to PSU(m+n) may be “on” supplying DCvoltages, but may be in “standby” due to the “standby” PAUs not drawingcurrents. When either a PSU or PAU failure occurs, the instant fail-overcan be achieved due to adequate DC energy being charged within the PAU.

FIG. 25 illustrates an alternate redundancy design for a power supplybank (PSB) that has (i+j) PSUs that form paralleling (i+j) redundancy.FIG. 25 shows the (i+j)PSB addition to the basic (m+n)CHPA. All theoutputs from power supplies 2501 to 25(i+j) may be summed at a DC bus251. Built-in series diodes, such as a diode 1501 in PSU 2501, may beused for the paralleling scheme. In a (i+j)PSB scheme, all PSUs may be“on” and supply equal currents to a common DC output to the CHPA. Whenone of the PSUs fails, the system may operate normally with the (i+j−1)PSUs supplying the needed current for CHPA, and may be shut down whenthe PSU failures exceed j. Therefore, the architecture may not providegraceful degradation due to PSU failures; but it may support gracefuldegradation operation due to PAU failures.

This configuration may allow the transmitter system to have a smallnumber of PSUs, thus providing a smaller profile and potentially lowercost. However, the configuration may introduce a common DC bus failurewhich may be in the critical path, and thus compromise MTBCF and Aoperformances. Additionally, a single DC “short” failure in any one ofPAUs may bring down system operation. However, when power, powerdensity, and reliability are equally important, the disclosedconfiguration may provide an optimal trade-off.

Therefore, to support the example 40 kW (9+1)CHPA, a (i+j)PSB, with i=2and j=1, may be used with 2.75 kW power supplies.

FIGS. 26A and 26B illustrate two views of a (2+1)PSB configuration withthe same height and depth dimensions as in a (9+1)CHPA, so that a(9+1)CHPA and a (2+1)PSB can be readily integrated as one entity. ThePSB may include three 2.75 kW PSUs 2600, 2602, and 2603. Two of thethree PSUs may adequately support a 4.8 kW maximum DC consumption of the(9+1)CHPA as specified in Table 3.

Mechanical wedge locks, like mechanical wedge locks 26033 and 26034, maybe designed to cause their associated PSU to be placed against or to beremoved from a power supply water cooling plate 26032. This may enable afailed PSU to be removed using “hot-swapping.” The PSB may have a +440VAC three phase input 2661, DC terminals 2662 for CHPA DC interfaces, awater inlet 2663, a water outlet 2664, and Ethernet interfaces 2665-2667from the PSUs to the ICU in the (9+1)CHPA.

FIGS. 27A-27C illustrate various components in an example of a (9+1)CHPAand (2+1)PSB set up for an SPS-49 platform. The setup may include a GFE,including an antenna and waveguide assembly, a transmitter including a(9+1)CHPA and a (2+1)PSB, and a radar signal processor suite. Aperipheral rack 2703 may be included.

An ultra-high power, such as hundreds of kWs, SSTx may be achieved bycombining several of the disclosed CHPAs and PSBs utilizing reliable andproven passive combining technology. Such an SSTx scheme may provideunprecedented solid state power and reliability due to the highreliability of its major sub-assemblies, such as the CHPAs and PSBs.

FIG. 28 illustrates an example of a more than a 280 kW SSTx thatcombines eight modular redundant (9+1)CHPAs utilizing hybrid combinersto replace a legacy Klystron transmitter for an SPS-49. For the RF path,a small signal may be input at an input port 281 and boosted and dividedby an input driver and divider module (IDDM) 2801 into 8 outputs, one toeach of eight (9+1)CHPAs 2802-1 to 2802-8 through gain/phase adjustors2807-1 to 2807-8 providing 80 W nominal inputs to the CHPAs 2802-1-8.Each CHPA 2802-1-8 may reliably deliver 36.6 kW minimal power. An outputcombiner module (OCM) 2803 may sum the input powers to greater than 280kW and deliver this to an RF output 282. The OCM may include reliablepassive hybrid couplers with more than 1 million hours MTBF and thus maynot degrade the MTBCF of the SSTx.

Redundancy in the IDDM may ensure that all sub-assemblies in thecritical path having greater than 100 kW MTBCF. Thus, the RF path mayoffer outstanding MTBCF.

Regarding the power supply scheme, there may be 8 redundancy (2+1)PSBs2804-1 to 2804-8 to support the CHPAs. In addition, PSUs 28016 and 28017may supply power to driver amplifier units (DAUs) 28012 and 28013utilizing the previously disclosed “one power-to-one PAU” scheme.

A PSB 2805 may be a (1+1) and provide parallel redundancy reliably toall system control needs. Therefore, the power supply path from aprimary input 284 to the DC outputs may be reliable.

The disclosed SSTx may also provide cooling water, such as the existing29 GPM to a manifold 2808-1 to remove heat from the CHPAs, the existing8 GPM to a manifold 2808-3 to cool the PSUs, and another existing 8 GPMto a manifold 2808-2 for other system application heat removal. An ICU2806 may monitor and control all sub-assemblies through an Ethernet port283. This approach may outperform a legacy Klystron radar transmitter.

Example specifications for the disclosed SSTx are summarized in thefollowing Table 4:

TABLE 4 Specifications for 280 kW SSTx for SPS-49 Radar UtilizingMultiple CHPAs Parameter Value Comments 1. Electrical Performance 1.1Operating 850-942 MHZ Minimum, Upper and Frequency Lower −1 dB Point 1.2RF Output 84.47 dBm/ Min/Max,; Power, peak 85.47 dBm 280 kW/352 kW; 1 dBVariation 1.3 RF Input 11.0 dBm Nominal, +/−1.0 dB Power, peak (80 W)1.4 Spurious 60 dBc Minimum, from Output 962-1212 MHz 1.5 Harmonic 30dBc 2nd, Minimum Output 40 dBc 3rd-5th 1.6 Input/output 1.5:1 MaximumVSWR 1.7 Output VSWR 2:1 Minimum, all phase Survival 1.8 Pulse Width2-64 μsec AV1: 32 uS max; AV2: 50 uS max 1.9 Pulse Duty 6% Max, AV1:3.87% max; Factor AV2: 4.5% max 1.10 Rise/Fall Time 0.08-0.8 μsec 10% to90% Power Point; 90% to 10% Point 1.11 Pulse Droop 0.25 dB Maximum, 10%to 90% time of 32 μsec Pulse 1.12 Pulse Phase 6 degrees Maximum, from 5μsec Variation after leading edge to 5 μsec prior falling edge with 32μsec Pulse 1.13 Pulse Phase 0.03 degrees Maximum Stability RMS 1.14Pulse Amplitude 0.01 dB RMS Maximum Stability 1.15 Power Efficiency37.2% Minimum 1.16 Primary Power 42.6 kW at AV2: 42.6 kW max; 440 VAC 3φ(4.5% DF) 2. Physical Parameter 2.1 Outline Rack: Two 901D Rack; AlsoDimensions 36″(L) × Retro-fit Feasible 32″(W) × 68″(H) 2.2 Weight 4,000lb ROM, Including Racks 2.3 Connectors TNC In, WR975, Option: Original3⅛″ RF Ethernet Output Interface 3. Thermal Parameter 3.1 WaterInlet/Outlet TBD Compatible to Existing Connectors Cooling Interfaces3.2 Flow Rates 45 GPM Nom, Existing 29 GPM, 8 GPM, 8 GPM Sources 3.3Inlet 43.3° C./50 psi Maximum Temp/Pressure

Driver amplifier units (DAU) 28012 and 28013 may provide automaticredundancy for the SSTx and thus may reduce system down time in the RFchain to minimal. The driver redundancy may include two RF switches28011 and 28014 to form a (1+1) redundancy scheme. The RF switches mayensure uninterrupted operation with driver amplifier failures.

The DAU 28012 may nominally be “online” and the DAU 28013 may nominallybe in “standby.” When DAU 28012 fails, a built-in controller of the DAUsmay send a fault signal to the ICU 2806, then the identical automaticfail-over scheme as in (m+n)CHPA can be achieved in IDDM. Therefore, theDAUs may also not be in the critical path and may not degrade the MTBCFof IDDM.

Switches 28011 and 28014 and a passive hybrid divider 28015 may be highreliable components. Thus, the MTBCF of the IDDM may be high. Inaddition, DAU “hot-swap” may be implemented in the same way as thecorresponding PAU scheme.

FIGS. 29A-29E illustrate examples of various components that may be partof an ultra-high power SSTx. FIG. 29A illustrates a CHPA module; FIG.29B illustrates a PSB module; FIG. 29C illustrates an IDD module withPSUs; FIG. 29D illustrates an ICU module located in an IDDM; and FIG.29E illustrates a 4-way OCM with an output coupler (the proposed 280 kWSSTx may include two 4-way OCMs).

The disclosed modular design offers a hatchable solution forinstallation and maintenance requirements of replacing the existingtransmitter. The design may include a modular CHPA and power supply bank(PSB), IDDM, OCM, and an interface control module (ICM). Each module,with manageable dimensions and weight, can be integrated and testedindependently, then transported through the “hatch” of a ship andintegrated into an SSTx rack. The modular approach may make transmitterupgrades practical, may ease maintenance complications, and may increasesystem availability by reducing MTR.

In the IDDM design, a card cage assembly may be designed to house theDAUs and their corresponding PSUs and to support DAU and PSU“hot-swapping.” The interface control module (ICM) may fit inside theIDDM car cage. The OCM design may be a 4-way combiner with the outputdirectional coupler, and two 4-way OCM may be included for the proposed280 kW SSTx. The 4 input 1⅝″ EIA ports in FIG. 29E may interface withthe CHPA directly via 7/16 DIN to 1⅝″ EIA Adaptors. A 3⅛″ EIA RFconnector at the output of the OCM may match the original systeminterface to an LPF (Low Pass Filter, GFE Unit #17)

The disclosed CHPA and PSB designs may provide significantly higherstandards for operational availability (Ao), reliability, andmaintainability, while reducing total cost of ownership by adapting to ashipboard environment, scalable (m+n) transmitter architecture, forcoherent transmitters. The (m+n) main building blocks may be part of thecombining high power amplifier design and a redundant power supply bankmay support true hot-swapping, automatic fail-over, and graceful powerdegradation.

FIG. 30 illustrates an example of a legacy SPS-49 transmitter. FIG. 31illustrates an example of a solid state upgrade to this legacytransmitter following the teaching herein that used only two existingbays, leaving the middle bay for maintenance access. The CHPA bay mayenclose 8x(9+1)CHPAs, the IDDM, and the ICM. The PSB bay may be occupiedby 8λ(2+1)PSBs. The hatched LRUs may be in “standby”.

A feasible solid state upgrade may include a thorough analysis of theSPS-49 radar specifications and site surveys. The disclosed SSTxconfigurations may outperform the existing transmitter, and may includesound mechanical and thermal management properties. The dimensions ofthe building blocks may be developed to meet retrofit requirements,

FIG. 32 illustrates an alternative forward fit upgrade proposal for theSPS-49 radar transmitter using two 901D racks 3201 and 3202. Each mayhouse 4 CHPA/PSB assemblies. In addition, an IDDM and ICM may beenclosed in the rack 3202. Separation of the two racks may supportinstallation and maintenance access which may eventually increase systemavailability by decreasing the MTRs of LRUs. The disclosed forward-fitSPS-49 Tx upgrade may simplify the design, system integration, and rigidenvironmental qualification procedures.

A cable-less version of the CHPA may provide even greater advantages tothe SPS-49 upgrade activity from mechanical packages and costperspectives. A cable-less CHPA may integrate the SCU, the powerdivider, and the RF input switches into a divider/switching combinerunit (DSCU). Although the advancement may introduce another level ofcomplexity, it may significantly reduce the implementation costs of an(m+n) SSTx, without compromising availability, reliability, ormaintainability.

FIG. 33 illustrates an example of a 10-way input power divider (DIV) andswitching combiner unit (SCU) combined into a single unit (DIV/SCUcombo). As illustrated in FIG. 33, ten pairs of input/output,phase-matched cable assemblies may connect 10 PAUs with a 10-way dividerand a (9+1)SCU. The high power, low-loss, phase-matched cables may havea very large inner bending radius. This may introduce significantphysical volumetric growth into the CHPA modular assembly. As a result,6.8 W/in³ power density may be achieved in a 40 kW (9+1)CHPA design, asillustrated in FIGS. 21A and 21B.

The matched cables may mechanically increase the challenge ofintegrating a 280 kW SSTx into an existing transmitter cabinet. Inaddition, cable assemblies may also affect the stability and theconsistency of the daily transmitter operation, especially in ashipboard environment. The removal of ten, high-power, phase-matchedcables may dramatically increase overall transmitter reliability due tothe elimination of high tension bends, joints, and a reduced number ofconnections.

Cost reduction considerations in a 280 kW SSTx utilizing (m+n)SSTxarchitecture may dictate an advanced DSCU development. A cost analysisbased on cable assemblies used in a CHPA/PSB demonstration programsuggests that removing phase-matched cables may save more than $300,000in materials and also may dramatically reduce assembly time. The totalcost reduction for a 280 kW SSTx may therefore exceed $1 million due tothe introduction of a DSCU. Furthermore, the disclosed DSCU approach maydramatically improve system maintainability.

As an example, a (7+1)DSCU design is used to explain the discloseddesign approach, which may include an 8-way input power divider, 8 RFinput switches, and a (7+1)SCU. Based on possible dimensions of RFinterfaces in the PAU, various design approaches may be achieved throughgeometric or trigonometric analysis.

FIG. 34A illustrates an example of an input/output constellationarrangement of connectors in a DSCU design that may connect to multiplePAUs. FIG. 34B illustrates an example of a back side of a PAU configuredto slidably engage connectors on the DSCU illustrated in FIG. 34A. Thebranches may be equal in electrical length, and there may be minimalpenetration interference between the DIV and the SCU assemblies. Allinputs and outputs of the PAUs may fall on two separate circles, one forthe inputs and one for the outputs. For example, all TNC RF inputs maybe landed on one circle, while all SC RF outputs may be landed on thesecond circle, each with a 5.739″ radius. This may cause the electricallengths from the center of the SCU to each PAU output port to be thesame, and the electrical lengths from the center of the DIV to each PAUinput port to be the same.

In the path from the SCU to each PAU output, there may be a λ/4 line,followed by a high power RF switch and then a transmission line to theSCU input. In the path from the center of the DIV to each PAU input,there may be a dividing branch, followed by the RF switch and then atransmission line to each DIV output.

FIG. 34A also illustrates an overlay between the DIV and the SCU, withfour RF interfaces on one assembly penetrating into the other one. TheSCU may be in front of the DIV or the other way around. When in front,long TNC barrels on TNC connectors 34011, 34021, 34031, and 34041 maypenetrate through the SCU, with the TNC connectors 34021 and 34031 atthe center line of the SCU and an SCU output 342 at the mid of the TNCconnectors 34021 and 34031 of the DIV. This may keep the penetrationinterferences to the RF paths at a minimum. The other TNC connectors34051, 34061, 34071, and 34081 on the DIV may not penetrate through theSCU due to the offset between DIV and SCU.

FIG. 35A illustrates another example of an input/output constellationarrangement of connectors in a DSCU design that may connect to multiplePAUs with uniform angle separation between adjacent branches. FIG. 35Billustrates an example of a PAU configured to slidably engage connectorson the DSCU illustrated in FIG. 35A. In this arrangement, adjacent RFpaths may be uniformly separated with 36° to achieve uniform RFperformance. The total electrical lengths may equal 5.855″ (the sum of5.562″ and 0.293″, or the sum of 4.854″ and 1.00″), and there may beminimal overlay interferences. In addition, a minor input connectorlocation adjustment of the PAU may be necessary to achieve the desiredarrangement. In the case of placing the SCU in front of the DIV, TNCconnectors 35011, 35021, 35031, and 35041 may similarly penetratethrough the SCU, while 35051, 35061, 35071, and 35081 may not penetratethe SCU.

FIG. 36A illustrates another example of an input/output constellationarrangement of connectors in a DSCU design that may connect to multiplePAUs with uniform angle separation between adjacent branches. FIG. 36Billustrates an example of a PAU configured to slidably engage connectorson the DSCU illustrated in FIG. 36A. In this optimal constellationarrangement, each branch in the SCU may travel the identical electricalpaths, including a 3.88″ line and a 1.949″ line. The penetrationapproach follows the one in FIGS. 34 and 35. FIG. 36C illustrates thedetailed circuit layout, including 8 identical switch assemblies and 8transmission line assemblies for SCU.

As illustrated in FIG. 36A, there may be uniform RF sub-assemblyarrangements with 36° separation between the adjacent branches using thesame sub-assemblies as the ones for the SCU shown in FIG. 36C. Theswitch assemblies, such as a switch assembly 3601, may each have a 3.88″electrical length in the SCU and the switching PIN diodes may be locatedλ/4 away from the center of the SCU. The transmission line assemblies,such as a transmission line assembly 3602 may each have a 1.949″electrical length and may be laid-out using micro-strip line replacingcable in the DIV/SCU combo assembly.

FIGS. 37A and 37B illustrate different views of an example of interfaceconnections between a switching assembly and a transmission lineassembly, and then to an interface of a PAU. These may be used in thecable-less DSCU illustrated in FIGS. 36A and 36C.

FIGS. 38A and 38B illustrate different views of an example of interfaceconnections between a divider assembly and a switch assembly, and thento an interface of a PAU input.

FIGS. 39A and 39B illustrate different views of an example of a(7+1)DSCU design and a significant proportional profile reduction incomparison to the DIV/SCU combo assembly shown in FIG. 33. Both the DIVand SCU may be used in the cable-less DSCU illustrated in FIGS. 36A and36C and may be based on the previous (9+1)SCU and 10-way DIV designswith two opposite branches being removed for the connector penetrations.TNC connector 391 is the input to DIV and 7/16 DIN connector 392 is theoutput of SCU. Pairs of 39011 and 39012, 39021 and 39022, 39031 and39032, 39041 and 39042, 39051 and 39052, 39061 and 39062, 39071 and39072, and 39081 and 39082 are to the 8 PAUs TNC inputs and SC output.

The drawings do not illustrate details of how to achieve a (7+1)SCU and8-way DIV. They are similar to (9+1)SCU and 10-way DIV detailedpreviously with two opposite branches removed for penetrations, butrather illustrate how to channel the individual port to the surface ofPAUs.

In FIG. 37, an output port 371 may be connected to a center point 372 ofa spider pin assembly 3702 through a transformer assembly 3701. Thespider pin assembly 3702 may include 8 output pins. One pin may connecta switch assembly 3703 at a port 373, while another port 374 may connecta transmission line assembly 3704 located on the other side via an RFfeed through to a via hole 377. Then, an SC RF input connector 376 (froma PAU) may directly interface with the transmission line assembly 3704at a junction 375. All other seven branches may be identically laid outfollowing the same approach.

In FIG. 38, an 8-way divider 3801 may be produced by removing twoopposite branches from the previous 10-way DIV. An RF signal input 381may be divided between 8 output ports, such as an output port 382. Aninput 383 of the RF switch, such as an RF switch 3802, may be mated withthe output port 382 via an SMP connection. Then, an output 384 of theswitch can directly interface a TNC connector 385 on the far side.

Control signals may be input at a D-sub connector 386 and then routed toindividual switches through an interface board 3803. FIGS. 38A and 38Balso show an opening on the DIV/SW assembly for penetration of an SCUoutput port.

The (7+1)DSCU design shown in FIGS. 39A and 39B may be used toconsolidate the device in FIGS. 37A and 37B with the device in FIGS. 38Aand 38B. Compared to the DIV/SCU combo assembly design shown in FIG. 33,the DSCU design in FIG. 39 may have a dramatically decreasedproportional volume. A common RF input at the TNC connector 391, RFoutput at the 7/16 DIN connector 392, SW control 393 on DIV, and SCUcontrol ports 394 may be located on one side. Eight pairs of TNC/SCconnectors (or barrels) may be located on the other side to directlyinterface with 8 PAUs.

FIGS. 40A and 40B illustrate different views of an example of a 30 kW(7+1)CHPA utilizing a (7+1)DSCU for ultra-high power RF with a highpower density. The self contained, ultra-high power amplifier module mayreceive an RF input signal at an input port 407 and deliver about 30 kWpeak power at an output port 408. It may be powered by single 50 VDCfrom a connector 404 and monitored and controlled via signals at anEthernet port 403. About 3.2 GPM of water may flow into an inlet 405,remove heat from the various LRUs, and then exit an outlet 406.

The disclosed (7+1)CHPA architecture may use a DSCU that places the ICUin the center surrounded by 8 PAUs. All of the LRUs may then be easilyaccessed for installation and maintenance. Reliable components may belocated in the back of a card cage.

Compared to the previously-discussed 40 kW (9+1)CHPA design, the volumeof 30 kW (7+1)CHPA may be significantly reduced proportionally. Thepower density may also be improved from 6.8 W/in³ to 12 W/in³, whichrepresents a 76% power density improvement.

One or more of the various designs that have been discussed may provideone or more of the following features:

-   -   An (m+n) redundant CHPA architecture that includes an (m+n)SCU,        (m+n) PAUs, and an (m+n)-way DIV. The (m+n) DIV may divide an        input signal equally to (m+n) ports. “M” online PAUs may amplify        their input signals into high power outputs with uniform        amplitude and phase characteristics, while “n” offline PAUs may        isolate their input signals from further propagating to the        (m+n)SCU. “M” on ports of the SCU may coherently sum up “m”        amplified signals, while “n” off ports may isolate any reflected        signal back to “n” PAUs. When one of the “m” PAUs fails, one of        the “n” PAUs in standby may fail over to replace the failed        unit, the corresponding off port of SCU may be switched on, and        the port interfacing the failed PAU may be shut off. The        architecture may not allow a PAU failure to interrupt operation        of CHPA. Only the DIV and the SCU may be in the RF critical        path. These DIV and SCU designs may ensure a CHPA redundant        architecture with high operation availability (e.g., about        99.99%) with an output reaching from 10 s to 100 s of kW.    -   The disclosed CHPA architecture may use an interface control        unit (ICU) that communicates with a control module in the PAUs        and controls the SCU accordingly. A PAU controller in each PAU        may report the health conditions of the PAU, including DC,        temperature, and RF parameters. When a key parameter of a PAU        falls out of normal range, such as output power, the controller        may quickly report the fault to the ICU. The ICU may        automatically place the failed PAU offline and put one of the        standby PAU's, if available, online, while turning on the        correspondent input port of the SCU. Therefore, automatic fail        over and uninterrupted operation may be achieved.    -   An RF switch may be placed before the RF input of a PAU and may        be controlled by a positional switch. The DIV, PAUs, and SCU may        interconnect with blind mate RF connectors and RF barrels may be        inserted between PAUs and the DIV/SCU output/input ports (FIGS.        2 and 3). The blind mate connectors may facilitate easy removal        and replacement of failed PAUs. This configuration may allow        system maintenance without operational interruption. The RF        switches and barrels may ensure good mechanical engagement of        the RF interfaces when a PAU is “hot-swapped.” At the same time,        the architecture may prevent large harmful radiation, both when        a PAU is present and removed, thereby facilitating safe        operation.    -   The SCU design may provide both efficiency and graceful        degradation. It may include high power RF switches to all input        ports, among which “m” ports may be initially switched on and        “n” ports may initially be switched off (FIG. 5). Thus, the SCU        may provide redundancy in the combining scheme. When one of “m”        PAU connected to the SCU ports fails, one of “n” ports, if        available, can be placed into the ‘on’ position, so that the        output impedance and power output of the SCU is unchanged. Even        with (n+1) failed PAUs, the SCU may present m/(m−1)*50Ω, instead        of 500 nominally with less than “n” failed PAUs. The larger the        value of “m,” the closer the SCU output impedance may be to 50Ω.        For example, for m=9, the VSWR of SCU may be 1.125:1 when 8        ports are on. Therefore, the graceful degradation may be        achieved with outstanding combining efficiency.    -   A high isolation passive DIV design with built-in terminations        may divide the input signal uniformly and constantly no matter        how output ports are matched (FIG. 7). Built-in terminators to        each output port may independently absorb reflected signal from        its corresponding port. Thus, the absorbed signal may not be        superimposed onto other output ports.    -   The high-density SSHPA design (PAU) may reduce overall profile        and increase overall power density. A T-plate structure may have        three significant planes—two opposing horizontal on each of        which are mounted power devices and one vertical plane that may        interface to a cooling plate. The structure may double power        density when compared to conventional layout architectures,        minimizing power amplifier profile. High thermally conductive        material may be embedded between the two horizontal surfaces        which may effectively transfer heat onto the vertical surface to        interface with the cooling plate. The approach may be used with        any power amplifier (e.g., FIG. 9).    -   The liquid cooling system can further reduce the profile of the        (m+n)CHPA and thus increase its power density. (FIG. 10).    -   A modular redundant (9+1)CHPA architecture (FIGS. 22 and 23) may        deliver 40 kW peak power. Multiple (m+n)CHPAs may be        conventionally combined to achieve 100 s of kW peak power in a        scalable, solid state, coherent radar transmitter, while        providing outstanding SSTx reliability and life cycle.    -   An (m+n) redundant power supply bank may be used with an        (m+n)CHPA (FIG. 24). There may be the same number of PSUs as        PAUs. All PSUs may initially be “on” with their DC outputs        present at the PAUs. “M” PSUs may be initially “online” due to        “m” “online” PAUs drawing currents; and “n” PSUs may be in        standby due to “n” standby PSUs not drawing currents. When one        of “online” PSUs fails, its controller may shut down the DC        output to its corresponding PAU. One of “standby” PSU may then        automatically fail-over due to its corresponding PAU being        automatically placed “online.” Therefore, automatic fail-over        and uninterrupted operation of (m+n)PSB may be achieved via its        (m+n)CHPA. Then, the MTBF of the PSU can be excluded from a        MTBCF calculation of the system which may consist of one pair of        (m+n)CHPA and (m+n)PSB. Thus, the (m+n)PSB architecture may not        result in system availability (Ao) degradation. Graceful        degradation with more than “n” PSU failures and hot-swapping may        also be achieved in an (m+n)CHPA.    -   The PSB may instead be configured with (i+j) PSUs to form        paralleling (i+j) redundancy (FIG. 25). In an (i+j)PSB        architecture, all PSUs may initially be “on” and equally supply        current to a common DC output to the CHPA. When one of the PSUs        fails, the system may still operate normally with (i+j−1) PSUs        supplying the needed current for the CHPA. The system may shut        down with more than (i+j) PSU failures. This architecture may        not provide graceful degradation due to PSU failures, but can        support graceful degradation due to PAU failures. This        configuration may allow the transmitter system to be designed        with a small number of PSUs, providing a smaller profile and        lower cost. However, the configuration may be subject to a        common DC bus failure and be in the critical path, thus        compromising MTBCF and Ao performance. A single DC “short”        failure in any one of PAUs may bring down system operation.        However, when power, power density, and reliability are equally        important, this alternative configuration may provide an optimal        trade-off. Therefore, to support an example 40 kW (9+1)CHPA, a        (i+j)PSB, with i=2 and j=1, has been presented with 2.75 kW        power supplies (FIG. 26).    -   Ultra-high power, such as 100 s kW SSTx, may be achieved by        combining multiple CHPAs and PSBs utilizing the combining        technology that has been disclosed. The disclosed SSTx scheme        may provide unprecedented solid state power and reliability due        to the high reliability of its major sub-assemblies, such as the        CHPAs and PSBs. As an example, more than 280 kW SSTx may be        achieved by combining 8 redundant (9+1)CHPAs utilizing hybrid        combiners (FIG. 28).    -   A driver amplifier unit (DAU) (1+1) with automatic redundancy        for SSTx may reduce system down time in the RF chain to a        minimum (FIG. 28). Driver redundancy may include 2 DAUs and 2 RF        switches, and RF switches to ensure uninterrupted operation with        driver amplifier failures.    -   The modular design may provide hatch-ability for installation,        maintenance, and when replacing an existing transmitter (FIGS.        28 and 29). This design may use an input driver divider module        (IDDM), output combining module (OCM) and interface control        module (ICM). Each module, with manageable dimensions and        weight, can be integrated and tested independently, then        transported through a navy ship's hatch (hatch-able) and        integrated into the SSTx rack. The modular approach may make        transmitter upgrades practical and may ease maintenance and        increase system availability by reducing MTTR.    -   A retrofit upgrade proposal for SPS-49 radar transmitter has        been disclosed (FIG. 31). The upgrade may occupy two bays and        implement a full solid state transmitter using only two of the        existing SPS-49 cabinet bays. This may leave a middle bay        available for maintenance access.    -   A forward fit upgrade for the SPS-49 radar transmitter may use        two 901D racks (FIG. 32). Each rack may house 4 CHPA/PSB        assemblies.    -   A combined divider and switching combiner unit (DSCU) may        provide an (m+n)-way divider and an (m+n)SCU. The DSCU module        may eliminate all match cables from the DIV to the PAUs and from        the PAUs to the SCU.

Instead, direct interfaces with the PAUs may be provided. The (m+n)redundant CHPA may have a small profile (high power density), be easy tomaintain, and provide consistent reliability and a significant costsavings.

The components, steps, features, objects, benefits, and advantages thathave been discussed are merely illustrative. None of them, nor thediscussions relating to them, are intended to limit the scope ofprotection in any way. Numerous other embodiments are also contemplated.These include embodiments that have fewer, additional, and/or differentcomponents, steps, features, objects, benefits, and/or advantages. Thesealso include embodiments in which the components and/or steps arearranged and/or ordered differently.

For example, the disclosed systems may achieve uninterrupted operationunder pulse conditions, without missing a single pulse. However, someapplications may not mind losing a pulse. In that case, the ICU maydetect a fault condition in one of online PAUs and send a command toturn off an additional RF switch located at a significantly lower powerlevel place where hot switching may not harm the added switch. Then, thePAU may fails over instantly, without concern for potential damage toSCU and PAUs. The described methodology may operate under CW conditions.The system may lose its signal for a period of 20ρS only, then continueoperation. The disclosed power DIV may be used as a power combiner withcoherent signal inputs to the multiple output ports; then the DIV inputmay serve as the output.

Unless otherwise stated, all measurements, values, ratings, positions,magnitudes, sizes, and other specifications that are set forth in thisspecification, including in the claims that follow, are approximate, notexact. They are intended to have a reasonable range that is consistentwith the functions to which they relate and with what is customary inthe art to which they pertain.

All articles, patents, patent applications, and other publications thathave been cited in this disclosure are incorporated herein by reference.

The phrase “means for” when used in a claim is intended to and should beinterpreted to embrace the corresponding structures and materials thathave been described and their equivalents. Similarly, the phrase “stepfor” when used in a claim is intended to and should be interpreted toembrace the corresponding acts that have been described and theirequivalents. The absence of these phrases from a claim means that theclaim is not intended to and should not be interpreted to be limited tothese corresponding structures, materials, or acts, or to theirequivalents.

The scope of protection is limited solely by the claims that now follow.That scope is intended and should be interpreted to be as broad as isconsistent with the ordinary meaning of the language that is used in theclaims when interpreted in light of this specification and theprosecution history that follows, except where specific meanings havebeen set forth, and to encompass all structural and functionalequivalents.

Relational terms such as “first” and “second” and the like may be usedsolely to distinguish one entity or action from another, withoutnecessarily requiring or implying any actual relationship or orderbetween them. The terms “comprises,” “comprising,” and any othervariation thereof when used in connection with a list of elements in thespecification or claims are intended to indicate that the list is notexclusive and that other elements may be included. Similarly, an elementpreceded by an “a” or an “an” does not, without further constraints,preclude the existence of additional elements of the identical type.

None of the claims are intended to embrace subject matter that fails tosatisfy the requirement of Sections 101, 102, or 103 of the Patent Act,nor should they be interpreted in such a way. Any unintended coverage ofsuch subject matter is hereby disclaimed. Except as just stated in thisparagraph, nothing that has been stated or illustrated is intended orshould be interpreted to cause a dedication of any component, step,feature, object, benefit, advantage, or equivalent to the public,regardless of whether it is or is not recited in the claims.

The abstract is provided to help the reader quickly ascertain the natureof the technical disclosure. It is submitted with the understanding thatit will not be used to interpret or limit the scope or meaning of theclaims. In addition, various features in the foregoing detaileddescription are grouped together in various embodiments to streamlinethe disclosure. This method of disclosure should not be interpreted asrequiring claimed embodiments to require more features than areexpressly recited in each claim. Rather, as the following claimsreflect, inventive subject matter lies in less than all features of asingle disclosed embodiment. Thus, the following claims are herebyincorporated into the detailed description, with each claim standing onits own as separately claimed subject matter.

The invention claimed is:
 1. A high power RF or microwave amplifier thatamplifies an RF or microwave input signal comprising: an input signaldivider (DIV) that has an input port that receives the RF or microwaveinput signal and that divides this input signal into multiple sub-inputsignals; multiple power amplifier units (PAUs), each having an inputport that receives an RF or microwave signal, an output port thatdelivers an amplified version of the received RF or microwave signal,and an interface port; an interface control unit (ICU) that communicateswith each PAU through its interface port and that: sets one or more ofthe PAUs to amplify one of the multiple sub-input signals (hereinafterreferred to as on-line PAU in on-line mode); monitors each on-line PAUto verify that it is operating within one or more pre-determined PAUspecifications; and upon detecting that one of the on-line PAUs is nolonger operating within the one or more pre-determined PAUspecifications (malfunctioning PAU), sets the malfunctioning PAU not toamplify one of the multiple sub-input signals and not to be available tobe switched to the on-line mode by the ICU (hereinafter referred to asoff-line PAU in off-line mode); and an output signal switching combinerunit (SCU) that coherently sums the outputs of the on-line PAUs anddelivers this to an output port.
 2. The high power amplifier of claim 1wherein the ICU: sets one or more of the PAUs not to amplify one of themultiple sub-input signals and to be available to be switched to theon-line mode (hereinafter referred to as standby PAU in standby mode);and upon detecting a malfunctioning on-line PAU, changes one of thestandby PAUs to the on-line mode, thereby causing suchpreviously-standby PAU to amplify one of the multiple input signals andto thereby replace the malfunctioning on-line PAU.
 3. The high poweramplifier of claim 2 wherein the ICU: monitors each standby PAU toverify that it is operating within the one or more pre-determined PAUspecifications; and upon detecting that one of the standby PAUs is nolonger operating within the one or more pre-determined PAUspecifications (malfunctioning standby PAU), changes the malfunctioningstandby PAU to the off-line mode, thereby preventing the PAU from beingone of the standby PAUs that is changed to the on-line mode in responseto detection of a malfunctioning PAU.
 4. The high power amplifier ofclaim 2 wherein: the input signal includes a series of pulses; and theICU begins and completes both of the following between two sequentialpulses in the series of pulses: changes a malfunctioning PAU to theoff-line mode; and changes one of the standby PAUs to the on-line mode.5. The high power amplifier of claim 4 wherein the pulses have aduration of no less than 1 μs and a period between pulses of no lessthan 20 μs.
 6. The high power amplifier of claim 2 wherein the ICU andthe SCU isolate the standby and off-line PAUs from the output of the SCUand the outputs of the on-line PAUs.
 7. The high power amplifier ofclaim 1 wherein the high power amplifier automatically shuts down afterthe ICU detects more than a pre-determined number of malfunctioningon-line PAUs.
 8. The high power amplifier of claim 1 wherein the outputport of the SCU presents and maintains a substantially constantimpedance, notwithstanding changes in the number of on-line PAUs, solong as the changes do not reduce the number of on-line PAUs below athreshold.
 9. The high power amplifier of claim 2 wherein the SCUcontinues to coherently sum the outputs of the on-line PAUs and todeliver this to the output port, even when there is no PAU in thestandby mode to replace a malfunctioning on-line PAU.
 10. The high poweramplifier of claim 1 wherein a malfunctioning PAU can be safely removedfrom the high power amplifier and replaced with a replacement PAU duringoperation of the high power amplifier, without interfering with ordegrading the performance of the high power amplifier during or afterthe removal and replacement.
 11. The high power amplifier of claim 10further comprising one or more blind mate connectors that detachablyconnect each PAU to the high power amplifier through multiple electricalconnections.
 12. The high power amplifier of claim 1 wherein an on-linePAU can be deliberately or accidentally removed from the high poweramplifier during operation of the high power amplifier, withoutinterfering with or degrading the performance of the high poweramplifier during or after the removal.
 13. The high power amplifier ofclaim 12 further comprising a sense switch that senses the removal ofeach PAU from the high power amplifier and wherein the ICU quicklyplaces any such removed PAU that is in the on-line mode into theoff-line mode before any of its multiple electrical connections arebroken by the continued removal of the PAU.
 14. The high power amplifierof claim 2 further comprising multiple power supply units (PSUs). 15.The high power amplifier of claim 14 wherein each PSU powers a differentone of the PAUs.
 16. The high power amplifier of claim 15 wherein theICU: monitors each PSU to verify that it is operating within one or morepre-determined PSU specifications; and upon detecting that one of thePSUs is no longer operating within the one or more pre-determined PSUspecifications (malfunctioning PSU): if the malfunctioning PSU ispowering an on-line PAU: changes the on-line PAU that is powered by themalfunctioning PSU to the off-line mode, thereby causing this on-linePAU not to amplify one of the multiple sub-input signals, not to beavailable to be switched back to the on-line mode by the ICU, and not toconsume power from its PSU; and changes one of the standby PAUs to theon-line mode, thereby causing such previously-standby PAU to amplify oneof the multiple input signals and to consume power from itscorresponding PSU, thereby replacing the malfunctioning PSU; and if themalfunctioning PSU is powering a standby PAU, changes the standby PAUthat is being powered by the malfunctioning PSU to the off-line mode.17. The high power amplifier of claim 1 wherein the high power amplifierautomatically shuts down when the ICU detects more than a pre-determinednumber of malfunctioning PSUs.
 18. The high power amplifier of claim 14wherein all of the PAUs and outputs from all of the PSUs are connectedto a common power supply bus.
 19. The high power amplifier of claim 18further comprising a diode connected in series between each PSU and thecommon power supply bus that prevents a malfunctioning PSU from loadingthe common power supply bus.
 20. The high power amplifier of claim 14wherein the ICU: monitors each PSU to verify that it is operating withinone or more pre-determined PSU specifications; and upon detecting thatone of the PSUs is no longer operating within the one or morepre-determined PSU specifications (malfunctioning PSU), deactivates themalfunctioning PSU.
 21. The high power amplifier of claim 14 wherein anyof the PSUs can be safely removed from the high power amplifier andreplaced with a replacement PSU during operation of the high poweramplifier, without interfering with or degrading the performance of thehigh power amplifier during the removal and replacement.
 22. The highpower amplifier of claim 21 further comprising: one or more blind mateconnectors that detachably connect each PSU to the high power amplifierthrough multiple electrical connections; and a sense switch that sensesthe removal of each PSU before any of the multiple electricalconnections are broken.
 23. The high power amplifier of claim 1 whereinthe DIV and SCU are in a single common compartment.
 24. The high poweramplifier of claim 23 wherein the DIV and SCU are detachably connectedto the high power amplifier through one or more blind mate connectors.25. The high power amplifier of claim 1 wherein the PAUs and PSUs arewater cooled.
 26. The high power amplifier of claim 1 wherein all of thecomponents within the PAUs are solid state.
 27. The high power amplifierof claim 26 wherein the high power amplifier produces a peak poweroutput of at least 40 kW at a frequency of at least 800 MHz with atleast a 20% bandwidth.
 28. The high power amplifier of claim 27 whereinthe high power amplifier has a peak power density of at least 10 W/in³.29. The high power amplifier of claim 28 wherein the high poweramplifier has a mean time between critical failures (MTBCF) of at least80,000 hours in naval shelter environments with at least 3.87% pulseduty factor.
 30. The high power amplifier of claim 2 wherein the ICUremoves the input signal to DIV before setting the malfunctioningon-line PAU to the off-line mode and a standby PAU to the on-line mode.31. The high power amplifier of claim 2 wherein the ICU sets amalfunctioning on-line PAU to the off-line mode and changes one of thestandby PAUs to the on-line mode to replace it within no more than 20ρs(microseconds).